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MILITARY EXPLOSIVES 



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PREPARED IN THE OFFICE OF 
THE CHIEF OF ORDNANCE 



August, 1919 







WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1919 



1° 



Wab Department 

Document No. 947 

O^ce of The Adjutant General 

n. •* •• 

iUN 16 t»20 



• ■ • 



^J; lO'll 



WAK DEPARTMENT, 

Washington, August 14, 1919. 

The following publication, entitled " Military Explosives," is pub- 
lished for the information and guidance of all concerned. 
[461.1, A. G. o.] 

By order or the Secretary of War : 

PEYTON C. MARCH, 

General, Chief of Staff. 
Official : 

P. C. HARRIS, 

The Adjutant General. 



PREFACE. 



This publication has been prepared by the Explosives Section, 
Ammunition Division. Ordnance Department, United States Army, 
for use of the Ordnance Department in the instruction of student 
officers. 

A large portion of the original manuscript was prepared by Ca^>t. 
John A. Marshall, Ordnance Department, but it has been consider- 
ably enlarged and revised by Lieut. Col. C. G. Storm, Ordnance De- 
partment. Acknowledgment is also made of the assistance of Maj. 
J. Herbert Hunter, Ordnance Department; Capt. C. A. Tibbals, jr., 
Ordnance Department : and Lieut. J. E. Woods, Ordnance Depart- 
ment, in connection with the preparation and revision of the text. 

5 



CONTENTS. 



Page. 
Introduction 2 3 

PART I. PPvOFELLANTS. 

Chapteb I.— MANUFACTURE OF SMOKELESS POWDER. 
General 2(5 



Manufacture ■ 2< 

Picking of cotton 2 ° 

Drying of cotton 2 $ 

Nitrating ^ 

Du Pont mechanical dipper process 30 

Centrifugal process 30 

Pot process 30 

Thompson displacement process 31 

Purification 

Pulping 34 

Poaching 35 

Wringing 36 

Dehydration 37 

Mixing 40 

Pressing 40 

Graining and cutting 41 

Solvent recovery 4 - 

Drying 42 

Air dry treatment 42 

Water dry treatment 44 

Alcohol dry treatment 44 

Blending 45 

Chapter II.— GRANULATION OF SMOKELESS POWDER. 

General ** 

Shape of granulation - — 

Size of granulation 

Effect of weight of charge 50 

Effect of weight of projectile 51 

Effect of solvent on shrinkage of powder 51 

Effect of moisture and volatiles 51 

Effect of methods of drying 52 

Dry dimensions 

Web -' 54 

Perforation 5<J 

Diameter. 



Needle wire OVJ 

Pin circle 56 

56 



Slope of cone__: 

Quick powder — Slow powder 56 

7 



8 CONTENTS. 

General — Continued. Page. 

Calculation of average dry web 56 

Calculation of required dry dimensions 57 

Calculation of per cent shrinkage 58 

Calculation of die dimensions 58 

Measurement of green powder 59 

Failure of powder in ballistic tests 60 

Formulae for burning sui'faces 60 

Conclusion — General considerations 63 

Chapter III.— STABILITY OF SMOKELESS POWDER. 

Stability tests s 65 

Causes of instability 66 

Stabilizers 66 

Reworked powder . 67 

Storage of smokeless powder 68 

Chapter IV.— INSPECTION OF SMOKELESS POWDER. 

Analysis of cellulose 71 

Analysis of diphenylamine 72 

Analysis of mixed acids 73 

Analysis of alcohol 76 

Analysis of ether 77 

Du Pont nitrometer 77 

Analysis of nitrocellulose 79 

Analysis of smokeless powder 82 

Chapter V.— COMPOUND PROPELLANTS. 

Sporting ballistite and infallible powder 88 

E. C. powder 89 

Chapter VI.— BLACK POWDER. 

General 90 

Manufacture . 91 

Process 91 

Finishing 92 

Packing 93 

Inspection 93 

Use 94 

Methods of analysis 94 

Sampling r 94 

Moisture 94 

Potassium nitrate 94 

Sulphur 95 

Charcoal 95 

Ash 95 

Specific gravity 95 

Determination of granulation 96 

Moisture and ash, free analysis 96 

Determination of potassium 96 

Chlorides, chlorates, and perchlorates 97 

Storage 97 



CONTENTS. 9 

PART II. MILITARY HIGH EXPLOSIVES. 

Page. 

Introduction 99 

Chapter VII.— TRINITROTOLUENE (T. N. T.). 

General 100 

Properties 100 

Manufacture 102 

Purification 104 

Crystallization from sulphuric acid 104 

Crystallization from alcohol 105 

Sulphite purification 105 

Use 105 

Inspection 106 

Specifications 106 

Analysis and testing 107 

Solidification point 107 

Ash . 108 

Insoluble matter 108 

Moisture 108 

Acidity 10S 

Nitrogen 108 

Fineness 108 

Storage 108 

Chapter VIII.— AMMONIUM PICRATE (ENPLOSIVE D). 

General 110 

Properties 110 

Manufacture 111 

Reworking 112 

Use 112 

Inspection 112 

Specifications L 112 

Analysis and testing 113 

Moisture 113 

Insoluble material 113 

Ash 113 

Nitrophenols 113 

Ammoniacal nitrogen 113 

Sulphuric acid 114 

Nitrates 114 

Free ammonia 114 

Storage 114 

Chapter IX.— PICRIC ACID. 

General 115 

Properties 115 

Manufacture ! 116 

Phenol process 117 

Chlorbenzol process 117 

Catalytic process 117 

Use 118 



10 CONTENTS. 

Page. 

Inspection 118 

Specifications., 118 

Analysis and testing 118 

Solidification point 118 

Moisture 119 

Sulphuric acid 119 

Nitric acid 119 

Ash 119 

Insoluble matter 119 

Soluble lead 119 

Storage 120 

Chapter X.— NITROSTARCH EXPLOSIVES. 

General nature : 121 

Reasons for adoption 121 

Manufacture 121 

Chemical and physical properties '.-. 122 

Sensitiveness 123 

Stability 124 

Explosive properties : 125 

Use, military and commercial 126 

Care in storage and handling 126 

Inspection 127 

Specifications 127 

Methods of analysis 127 

Moisture ^ 127 

Ether extract 127 

Water extract 128 

Sodium bicarbonate 128 

Ammonium nitrate 128 

Sodium nitrate 128 

Charcoal . 128 

Nitrostarch 128 

Chapter XI.— TETRYL. 

Manufactured 129 

Chemical and physical properties 129 

Stability and sensitiveness 130 

Explosive properties 130 

Use, military and commercial 130 

Precautions in handling and storage 131 

Inspection 131 

Specifications 131 

Methods of testing 131 

Melting point 131 

Acidity 132 

Insoluble matter 132 

Ash 132 

Moisture and volatile 132 

Sodium salts 132 



CONTENTS. 1 1 

Chapter XII.— TETRANITROANILINE (T. N. A.). 

Page. 

Manufacture 133 

Chemical properties 133 

Toxic properties 334 

Sensitiveness to heat, shock, and friction 134 

Explosive properties . 135 

Use 135 

Precaution in handling and storage 136 

Inspection ' 130 

Nitrogen content 136 

Melting point - — 136 

Insoluble in acetone l 136 

Moisture 137 

Acidity 137 

Chapter XIII.— MERCURY FULMINATE. 

Manufacture 138 

Chemical and physical properties 139 

Impurities 139 

Action on metals 140 

Stability and sensitiveness 140 

Explosive properties 141 

Use 141 

Precautions in handling and storage 142 

Methods of analysis 142 

Acidity 142 

Insoluble matter 143 

Free mercury 143 

Mercury fulminate content 143 

Chlorides 144 

Chapter XIV.— AMATOL. 

General , 145 

Properties . 145 

Manufacture 145 

Analysis 145 



LIST OF ILLUSTRATIONS. 



PART I. SMOKELESS POWDER. 
Plate 
No. Page. 

1. Du Pont mechanical dipper process, nitrating floor, Smokeless Powder 

Factory, Picatinny Arsenal, N. J 30a 

2. Du Pont mechanical dipper process, wringing centrifugal floor, Smoke- 

less Powder Factory, Picatinny Arsenal, N. J 30b 

3. Du Pont mechanical clipper process, immersing basin and exit flume 

floor, Smokeless Powder Factory, Picatinny Arsenal, N. J 30c 

4. Nitrating pans, Thompson displacement process, Smokeless Powder 

Factory, Picatinny Arsenal, N. J 30d 

5. Schematic sketch of unit of nitrating house 31 

6. Exterior of boiling tub unit, Old Hickory Smokeless Powder Plant, 

Nashville, Tenn 32a 

7. Interior of boiling tub unit. Old Hickory Smokeless Powder Plant, 

Nashville, Tenn 32b 

8. Jordan pulping engine, and Hickory Smokeless Powder Plant, Nash- 

ville, Tenn 32c 

9. Jordan pulping engine unit, Old Hickory Smokeless Powder Plant, 

Nashville, Tenn 32d 

10. Miller-Duplex type beater, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 34a 

11. Interior of poaching house, Old Hickory Smokeless Powder Plant, 

Nashville, Tenn 34b 

12. Schematic sketch of packer pulp screen 37 

13. Operating floor, dehydrating press house, Smokeless Powder Factory, 

Picatinny Arsenal, N. J 36a 

14. Schematic sketch of dehydrating system 38 

15. Large dehydrating press, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 38a 

16. Mixer ready for discharge, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 40a 

17. Macaroni press, first stage, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 40b 

18. Macaroni press, final block, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 40c 

19. Graining press room, Smokeless Powder Factory, Picatinny Arsenal, 

N. J 40d 

20. Charging flooi% can type, solvent recovery house, Smokeless Powder 

Factory, Picatinny Arsenal, N. J 42a 

21. Can and discharge floor, can type, solvent recovery house, Smokeless 

Powder Factory, Picatinny Arsenal, N. J 42b 

22. Schematic sketch of Nos. 3 and 5 dry houses, Smokeless Powder Fac- 

tory, Picatinny Arsenal, N. J 43 

13 



14 ILLUSTRATIONS. 

Plate 
No. Page. 

23. Exterior of " continuous " process dry house, Old Hickory Smokeless 

Powder Plant, Nashville, Tenn 44a 

24. Interior of " continuous " process dry house, Old Hickory Smokeless 

Powder Plant, Nashville, Tenn 44b 

25. Cannon powder blender, Old Hickory Smokeless Powder Plant, Nash- 

ville, Tenn 44c 

26. Cannon powder blender,. Smokeless Powder Factory, Picatinny 

Arsenal, N. J 46a 

27. Hoisting belt in blender, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 46b 

28. Box filling and weighing floor, cannon powder blender, Smokeless 

Powder Factory, Picatinny Arsenal, N. J 46c 

29. Powder box testing house, Smokeless Powder Factory, Picatinny 

Arsenal, N. J 46d 

30. Powder die assembly used for cylindrical grains 53 

31. Die body, pin plate, plug, water jacket, water jacket head, and smoke- 

less powder grain for 12-inch gun 52a 

32. Sketch showing webs of cylindrical smokeless powder grain 54 

33. Sketch showing dimensions of cylindrical smokeless powder grains 55 

34. Granulation data card 64 

35. Mill for reworking unstable powder, Smokeless Powder Factory, Pica- 

tinny Arsenal, N. J 66a 



QUESTIONS ON THE TEXT OF " MILITARY EXPLOSIVES. 



INTRODUCTION. 

1. Differentiate between the term explosives and high explosive. 

2. Enumerate the phenomena occurring in sequence when a sub- 
stance is exploded. 

3. Define detonation. 

4. Enumerate the three general divisions noted into which mili- 
tary explosives fall. 

5. Define propellant. 

6. Give the distinguishing characteristics between a propellant 
and high explosive with examples of each. 

7. What criteria are used in selecting or rejecting a new substance 
for use as an explosive ? 

8. Are high explosives ever used alone or in combination with 
other substances to constitute a propellant? If so, when? 

9. In general, what are the types of chemical reactions which are 
involved in the decomposition of an explosive ? 

10. What function does a high explosive serve? 

Chapter I. 

1. Discuss briefly the historical development of nitro cotton. 

2. What differentiates nitro cotton from smokeless powder. 

3. Discuss from the physical and chemical standpoint the term 
smokeless powder. 

4. Define the phrase granulation of smokeless powder. 

5. Discuss the various types of granulation of smokeless powder. 

6. Classify the different processes involved in the manufacture of 
smokeless powder. 

7. What is pyro cotton? 

8. Differentiate between pyro cotton and smokeless powder. 

9. What is the necessity of purifying raw cotton. 

10. Describe the picking operation. 

11. What would be the effect of nitrating cotton having a higher 
water content than that given by specifications : 

(a) Upon the cotton? 

(b) Upon the acid? 

12. What are the points of difference and of similarity between the 
Thompson displacement system and the Du Pont dipper process ? 

15 



16 MILITARY EXPLOSIVES. 

13. Describe in detail the Du Pont mechanical dipper process. 

14. Describe in detail the Thompson displacement system of 
nitration. 

15. What degree of nitration is attained in the ordinary manu- 
facture of pyro cotton ? Indicate the nearest empirical formula. 

16. What considerations enter into the purification of pyro cotton \ 

17. How are these processes classified ? Describe each in detail. 

18. Discuss the Jordan engine. 

19. What considerations limit the operation of the Tolhurst 
wringer ? 

20. Define dehydration. What chemical principles are involved in 
this procedure? 

21. Discuss the operation of dehydration in detail. 

22. What is a stabilizer ? Where and why and how is it used ? 

23. Discuss the formation of the colloid, enumerating the several 
stages involved. 

24. Indicate in a general manner by diagram the method used in 
forming a grain of powder from the finished colloid. 

25. Define the term solvent recovery. Describe two different 
methods of accomplishing this operation. 

26. Discuss the air drying of powder. 

27. Does all powder receive air-dry treatment? If so, why? 

28. What do you understand by the terms water dry and alcohol 
dry? 

29. Describe the method of operation of a continuous drier. 

30. What do you understand by blending of powder? Describe 
its principles and practice. 

Chapter II. 

1. Define the following terms: 

Explosion. 

Detonation. 

Propellant. 

Ignition. 

Kinetic energy. 

Granulation of powder. 

2. What considerations govern the granulation of a raw powder 
grain ? 

3. Enumerate and describe briefly the different shapes of granu- 
lation. 

4. What considerations determine the size of a powder grain? 
Discuss each. 

5. Discuss the relationship of the different methods of drying to 
ballistics and stability of smokeless powder. 



MILITARY EXPLOSIVES. 17 

6. What is meant by web average ? Web inner ? Web outer ? 

7. Should the green dimension of powder correspond to the die di- 
mension? Discuss fully. 

8. What considerations influence the calculation of web measure- 
ments ? 

9. What is the basis of calculation for all the dimensions of the 
dried powder grain? 

10. Describe the method of measuring green powder. 

11. Discuss stability of smokeless powder from the standpoint of 
storage. 

12. Discuss the stability of smokeless powder from the standpoint 
of heat test, and from other general chemical view points. 

13. What is reworked powder? 

11. Indicate which of the following powders you would rework 
and why: 

12-inch gun manufactured prior to 1008. 
6-inch gun manufactured in 1910. 
0.30 caliber manufactured in 1909. 
J 2-inch mortar manufactured in 1911. 
Bull's-eye powder manufactured in 1910. 

15. What special considerations should be given the first two 
powders mentioned in the above question ? 

16. What processes of manufacture are concerned in the rework- 
ing of smokeless powder \ 

17. Indicate which of the processes are concerned : 

(a) Drying. 

(b) Nitrating. 

(c) Boiling tub. 
{d) Pulping. 
(e) Screening. 

18. Describe the process of manufacture of reworked powder. 

19. Discuss its points of similarity and difference with the manu- 
facture of straight smokeless powder. 

20. What are your ideas relative to the stability of finished re- 
worked powder? 

21. Define the term explosion? 

22. Differentiate between ignition, combustion, detonation, incen- 
dition. 

23. Differentiate between single and nmltiperforated grains, dis- 
cussing the web dimensions in each case. 

21. Describe the Walsh grain. 

25. What allowances must be made for shrinkage in determining 
die dimensions? 

132569—19 2 



18 MILITARY EXPLOSIVES. 

26. Show the differences and similarities between green dimen- 
sions, die dimensions, and dry dimensions. 

27. Give the formula for arriving at the determination of large 
" D." 

28. Upon what factors is the average web of the die dependent ? 

29. Discuss the failure of a lot of powder to pass the ballistic test. 
Assume that the powder develops an excessive pressure, state your 
recommendations as to what procedure shall be followed : (a) On the 
same lot of powder; (b) upon the calculation of die dimensions for 
a new lot of powder for use in the same type of gun. 

Chapter III. 

1. Discuss the term stability of smokeless powder. 

2. What is meant by stabilizer ? 

3. What is meant by an indicator ? 

4. Why is it necessary to rework powder ? 

5. What additional manufacturing processes are employed to re- 
work smokeless powder? 

6. Which ones are omitted? 

7. What considerations govern the selection of a site for storage 
magazines ? 

8. Discuss the problems connected with fire protection in relation 
to the storage of smokeless powder. 

9. How is smokeless powder stored? 

10. What precautions would you observe in the hiring of labor 
for work around powder magazines? 

11. Discuss the use of nonsparking tools. 

Chapter IV. 

1. What analyses are made upon raw materials entering into the 
manufacture of smokeless powder? 

2. What control tests are made during the manufacture of smoke- 
less powder? 

3. What is meant by the term moisture and volatiles? 

4. Do you differentiate between moisture and volatiles and total 
volatiles ? 

5. Enumerate the physical tests which are made on smokeless 
powder. 

6. What raw materials are tested in smokeless powder manufac- 
ture? 

7. Discuss in detail the tests made on any two raw materials. 

8. Describe the method of making a test for ether-alcohol insolu- 
ble material in nitrocellulose. 



MILITARY EXPLOSIVES. 19 

9. Describe the heat test at 65.5° C. 

10. What is meant by degree of fineness ? 

11. Describe the 135° test, 

12. Describe the method of making a determination for per cent 
nitrogen in nitrocellulose, 

13. How would you make a determination for ash in smokeless 
powder ? 

14. Describe the method of making moisture and volatile tests on 
smokeless powder. 

15. What manufacturing processes are concerned with the fol- 
lowing tests? 

(a) Moisture and volatile. 

(b) Degree of fineness. 

(c) K. I. test for nitrocellulose. 

(d) Determination of moisture content in raw cotton. 

16. How is powder stored? Describe the type of container used 
and discuss the salient points. 

17. How may smokeless powder be properly stored in magazines ? 

18. Discuss the topography of the country where magazines may 
be erected. 

19. Enumerate in detail what rules are to be observed in the 
storage of smokeless powder and high explosives. 

Chapter V. 

1. What is meant by the term compound propellants? 

2. Describe infallible powder, its use and manufacture. 

3. What is E. C. powder? 

4. Give a brief historical summary of black powder. 

5. Describe the manufacture of black powder. 

6. What tests are made on finished black powder? 

7. Describe any two tests. 

8. Discuss the storage of blac.k powder. 

9. Enumerate the different grades of black powder. 
10. Discuss the uses of any two grades. 

Chapter VI. 

1. When was black powder first used as a military explosive? 

2. When was black powder displaced as a propellant powder ? 

3. Give present military uses of black powder. 

4. Give composition of black powder. 

5. Describe briefly method of manufacture. 

6. In what grade of powder is hardwood charcoal used? 

7. Give method for determination of sulphur. 



20 MILITARY EXPLOSIVES. 

8. Give method for determination of chlorides, chlorates, and 
perchlorates. 

9. Describe determination of specific gravity. 

10. Give necessary precautions for storage and handling of black 
powder. 

Chapter VII. 

1. What is T. X. T.? 

2. How would you use it? (a) As a bursting charge, (b) in 
combination with mercury fulminate ? 

3. What grades of T. X. T. are specified and how do they differ 
from each other? 

4. What are the uses of each grade ? 

5. Describe the nitration processes involved. 

6. How may T. N. T. be purified? 

7. What criterion is used to determine purity during the manu- 
facture of T. N. T. ? Describe the test involved. 

8. How would you make a determination of ash on T. N. T.? 

9. Discuss the storage of T. N. T. 

10. Discuss T. X. T. poisoning. 

11. Describe the method of making the fineness test. 



"6 



Chapter VIII. 

1. Define ammonium picrate. 

2. For what purposes is ammonium picrate used ? 

3. Discuss the hygroscopicity of ammonium picrate as compared 
with other explosives. 

4. Describe the manufacture of ammonium picrate. 

5. What details of manufacture must be carefully observed to 
secure reddish crystals? 

6. How may ammonium picrate be reworked? 

7. Can you make a melting point determination of ammonium 
picrate ? How ? 

8. Describe briefly the determination of ammoniacal nitrogen. 

9. How is free ammonia determined quantitatively in ammonium 
picrate ? 

10. Discuss briefly the storage of ammonium picrate. 

Chapter IX. 

1. Discuss the uses of picric acid. 

2. Discuss its advantages and disadvantages for use as a high ex- 
plosive. 

3. How may some of these disadvantages be overcome? 

4. Describe the process of sulphonation, as practiced in the manu- 
facture of picric acid. 



MILITARY EXPLOSIVES. 21 

5. Discuss briefly the chlorbenzol process of manufacture. 

6. Discuss the physiological effect of picric acid upon the work- 
men. 

7. Describe the method of making a solidification point determina- 
tion on picric acid. 

8. Describe the method of making an ash determination on picric 
acid. 

9. Why is the presence of soluble lead in picric acid objectionable? 

10. Discuss briefly the storage of picric acid. 

Chapter X. 

1. What is the difference between " nitrostarch " and " nitro- 
starch explosives " ? 

2. Give reasons for the adoption of nitrostarch explosives by the 
Ordnance Department. 

3. What starch gives best results in manufacture of nitrostarch? 

4. Describe briefly methods of manufacture of nitrostarch. 

5. Give reasons for the use of oil in nitrostarch explosives. 

6. Compare sensitiveness with other military explosives. 

7. Give reasons for stability and instability. 

8. What precautions are necessary in the storing and handling of 
nitrostarch and nitrostarch explosives? 

9. State determination necessary in analysis of grenade powder. 

Chapter XI. 

1. Give chemical name for tetryl. 

2. Give briefly method of manufacture. 

3. State military uses. 

4. Give relative strength or power as an explosive. 

5. Give relative sensitiveness. 

6. Give method for determination of sodium salts. 

7. Give precautions necessary for handling and storage. 

Chapter XII. 

1. What is T. N. A.? 

2. Discuss briefly method of manufacture. 

3. Discuss toxic effects of T. N. A. manufacture. 

4. Compare T. N. A. with tetryl and T. X. T. as to— 

(a) Stability. 

(b) Sensitiveness. 

(c) Explosive properties. 

5. Give military uses and reasons therefor. 
G. Give method of determination of acidity. 

7. Give precautions necessary for handling and storage. 



22 MILITARY EXPLOSIVES. 

Chapter XIII. 

1. Describe the preparation of mercury nitrate. 

2. Give methods of combining the mercury nitrate and alcohol. 

3. Describe the appearance of fulminate crystals. 

4. What impurities must be avoided ? 

5. Describe briefly the stability and sensitiveness of fulminate. 

6. Give reason for using potassium chlorate with fulminate. 

7. What precautions are necessary in handling and storage? 

Chapter XIV. 

1. What is amatol ? 

2. Where and for what reasons was it adopted as a military ex- 
plosive ? 

3. What mixtures are authorized ? 

4. What is the effect of impurities in T. N. T. used ? 

5. What impurities are to be avoided in the ammonium nitrate 
used? 

6. Is amatol hygroscopic? 

7. What effect has amatol on copper or tin ? 



INTRODUCTION. 

An explosive may be defined, in general, as being a liquid or a 
solid substance, or mixture of substances, which upon application of 
a blow to a small portion of its mass or by a rise in temperature, is 
converted in a small space of time into other substances more stable, 
which are mainly gases or vapors, but may include solids. The chemi- 
cal changes thus produced develop a sudden rise in pressure in the 
surrounding medium, and the word " explosive " is applied as a gen- 
eral term to the different types of phenomena occurring in this sort 
of reactions. Coincident with this evolution of gas a considerable 
amount of heat is evolved which produces a flame. A high explosive 
is one in which this change occurs within the shortest space of time 
and the phenomenon accompanying this decomposition is termed a 
detonation. Detonation, therefore, applies, more properly, to the 
chemical reaction incident to the almost instantaneous decomposition 
of the high explosive; it is not properly employed, however, when 
discussing the analogous reaction incident to the combustion of a 
slower burning explosive as smokeless powder. The general term, 
explosive, which finds universal acceptance, applies alike to high 
explosives, black powder, and smokeless powder. It will be seen, 
therefore, that the accepted distinction between the different classes 
of explosives is based primarily upon their relative speed of decom- 
position, and only those explosives are classified as high explosives 
in which this chemical change is considered practically instantaneous. 

Berthelot (Explosives and Their Power — Trans : Hake & Macnab — 
John Murray, London) enumerates and distinguishes between eight 
different groups of explosive bodies which owe their transformation 
either to the application of some external circumstance, such as fire, 
shock, friction, or else to the aid of a secondary reagent or chemical 
agent which propagates within itself an explosive wave and finally 
accomplishes a general explosion. Of these eight groups the greater 
number of military explosives fall within the third, fourth, and 
eighth divisions : 

(a) Explosive inorganic compounds. — Definite bodies liquids o>- 
solids, as the azides. 

(b) Explosive organic compounds. — Definite bodies, liquids or 
solids, in which classification occurs the nitrated derivatives of 
the carbohydrates, as nitrocellulose, nitrostarch, and the nitrated 
derivatives of the aromatic compounds as trinitrotoluene. 

23 



24 MILITARY EXPLOSIVES. 

(c) Mixtures formed by oxidizable and oxidizing bodies, solid or 
liquid, neither of these being explosives separately, as. for instance, 
black powder, etc. 

Marshall (Explosives, Blakistons & Co., 1917, vol. 1) defines an 
explosion thus: "When gas or vapor is released so suddenly as to 
cause a loud noise an explosion is said to take place, as, for instance, 
the explosion of a steam boiler or of a cylinder of compressed gas." 
The barrel of the gun may be considered, at the time of the explosion, 
as being a cylinder of compressed gas. The walls of the gun con- 
stitute the walls of the cylinder, the breech mechanism one end, and 
the projectile the other. 

If an explosive were used which gave instantaneous detonation 
the force so generated would either burst the barrel of the gun or 
else (in the case of a reduced charge) would not impart sufficient 
velocity to the projectile to develop the maximum efficiency. This 
particular point illustrates the necessity of using a relatively slow 
burning explosive as the means of propelling the projectile from the 
muzzle of the gun, an explosive which may be designated as the pro- 
pelling charge or propellant. The compression in the powder 
chamber of the gun must be developed slowly at first, gradually in- 
creasing in intensity until the projectile, in the case of the ideal gun, 
is forced to the muzzle, at which place the maximum pressure of the 
charge is exerted. However, in actual practice the maximum com- 
pression in the gun is never developed at the muzzle, a condition 
which would cause bursting according to our present design, in which 
the maximum pressure is exerted just after the projectile starts 
moving from its original position; usually the maximum pressure 
occurs when the projectile is only 1 foot or so ahead of its original 
position. In this function of projecting a shot, the high explosive 
as such finds no application. It may occur, however, as a constituent 
of a propellant, as, for example, nitroglycerin, a high explosive 
which is an ingredient of certain sporting powders, pistol powders, 
and cordite powders. The field of usefulness of the high explosive 
as a class is quite different and advantage is taken of its properties 
of detonation to use it within the shell or other bursting projectile 
so that at the proper time the shell will be disrupted through the 
detonation of the high explosive with which it was filled. 

The present tendency is to draw a sharp distinction between two 
classes of explosive bodies in accordance with the use to which they 
are put and also in accordance with the speed of reaction whereby 
combustion or decomposition takes place ; for example : 

First. Those substances or mixtures whose rate of combustion is 
such as to permit their use for propelling projectiles from guns are 
termed propellants. 



MILITARY EXPLOSIVES. 25 

Second. Those substances whose rate of decomposition is so very 
high as to preclude their use as propellants, but which, on the other 
hand, bring about very powerful disruptive action. Such bodies are 
known as detonating explosives, disruptives, or more commonly, as 
high explosive. 

The different substances used for high explosives are very many, 
but at the present time one substance, with certain modifications and 
additions, is used as the base of the propelling charge. This sub- 
stance is a colloid formed by the action of a solvent upon a nitrated 
cellulose with or without the addition of nitroglycerin, and in its final 
form is called smokeless powder. 

The selection of these various substances is dependent upon their 
cheapness of manufacture and their safety in handling. In order 
that this data may be properly evaluated, it is necessary that the 
following properties and measurements be determined : 

First. The chemical equation involved in the change of the sub- 
stance from the liquid or solid to the gaseous state. 

Second. The thermo-chemical values as given in heats of formation 
of the different components. 

Third. Their specific heats. 

Fourth. Their densities. 

Fifth. The relative pressure which may be developed by comparing 
equal parts of a new explosive with that of one well known. 

Sixth. The type and amount of energy required to initiate reac- 
tion. 

Seventh. Rapidity of reaction. 

Eighth. The relative power of the explosive. 



CHAPTER I. 
PART I.— PROPELLANTS. 

MANUFACTURE OF SMOKELESS POWDER. 

General. — The first nitro cotton which was made was the result 
of an experiment performed in 1838, when Pelouze observed the 
action of nitric acid upon cotton. A few years later, in 1845, Schon- 
bein realized the importance of this material as an explosive and 
developed it to such a point that he endeavored to sell the product 
to various governments. Early attempts at the use of this new 
explosive, however, especially in Austro-Hungary, were fraught with 
disaster, for factories were destroyed, and guns were damaged as a 
result of unfamiliarity with the chemical and physical properties of 
this new substance. 

The unfortunate experiences, however, of the Austrians did not 
deter the English chemists from developing the industry. Promi- 
nent among these men at this time was Sir Frederick Abel, who 
started a small factory for the manufacture of nitro cotton at 
Waltham Abbey. The industry received tremendous support and 
the important progress which was made during the next few years 
was, in fact, responsible for the later developments of collodion- 
photography and for the artificial silk industry. 

During this period the use of gun cotton as an explosive was re- 
stricted entirely to blasting purposes. In seeking for a new material 
which might be used in place of black powder, and which would 
not have the objectionable features of the old propellant, as smoke, 
etc., it occurred to Schultze that gun cotton would be a possible sub- 
stitute for this purpose. Many different substances and compounds 
were experimented with, but the first ones to achieve any notable; 
success were the Schultze and the E. C. powders. These won in- 
stant recognition as shotgun powders, but proved too quick for use 
in rifled arms. 

About this time another important step in the development of 
smokeless powder was made by Vielle, a French chemist. He incor- 
porated nitro cotton with a mixture of ether-alcohol, and rolled the 
resulting paste, a colloid, into thin sheets, which were cut into small 
squares and dried. Contemporaneous with this work, Nobel de- 
veloped ballistite, a powder obtained by gelatinizing a low nitrated 
nitro cotton with nitroglycerin. Shortly after this, a modification 
of ballistite, known as cordite, was adopted as a smokeless powder. 
26 



MILITARY EXPLOSIVES. 27 

This propellant consisted of a mixture of high nitrated gun cotton 
gelatinized by means of acetone. In this mixture nitroglycerin and 
vaseline were incorporated. 

At the present time all nations use as a propellant either gelatin- 
ized nitro cotton alone, or else gelatinized nitro cotton mixed with 
vanning quantities of nitroglycerin. 

The term smokeless powder when considered from the exact mean- 
ing of the words is a paradoxical misnomer, for the substance is not 
entirely smokeless, and it is not a powder. 

It may occur in small flakes, strips, pellets, cylinders, or other 
different shapes, the cylinders varying in length from 1.45 milli- 
meters for 8 mm. gmn to 55 millimeters for a 16-inch gun. The 
accepted form of granulation of smokeless powder used in this 
country is that of a cylinder in which extend longitudinally one or 
more perforations throughout the grain. For the smaller size 
powders, as for instance 8 mm., .30 caliber, 1 pounder, etc., there 
is only a single perforation. The larger sizes, however, have seven 
perforations. There is no intermediate number of perforations, 
the grain either having one or else seven. 

In addition to the cylindrical form of granulation, the so-called 
Walsh grain, or sliverless grain, has been devised to meet certain 
conditions incident to the firing of mortars. Instead of being a true 
cylinder the grain is scalloped on the outer surface. There are six 
of these indentations, and they are so placed that the apex of the 
reentrant angle occurs exactly at a point midway between the six 
outside perforations. This form of grain accomplishes the im- 
portant function that it reduces the weight of the charge, for the 
reason that its combustion is practically complete. This is due to 
the fact that the burning surface is greater than that of the cylin- 
drical grain of the same length and the same diameter. This greater 
burning surface gives an increased rate of burning, with the result 
that where formerly there was a relatively large amount of uncon- 
sumed powder left after the charge had been fired with the use 
of this type of grain the slivers of unburned powder are practically 
eliminated. It dries also quite as well, if not better, than the cylin- 
drical grain and shows no tendency to split at the reentrant angles. 

MANUFACTURE. 

The different processes incident to the manufacture of smokeless 
powder may be summarized under the following heads : 

First. Purification and mechanical preparation of the raw cotton. 
This includes the picking and drying processes. 

Second. Nitration of the cotton. This is accomplished by treating 
the cotton with a mixture of nitric and sulphuric acids, thus produc- 
ing a cellulose nitrate or " pyro cotton." 



28 MILITARY EXPLOSIVES. 

Third. The purification of the " pyro " from all traces of free 
acids and lower nitrates. 

Fourth. The mixing of the pyro cotton with ether-alcohol to 
form a colloid. 

Fifth. The granulation of the powder b}' pressing the colloid 
through steel dies. 

Sixth. The final processes of solvent recovery, drying, and blend- 
ing. 

The details of manufacture are as folkrws: 

The cotton used in the manufacture of smokeless powder consists 
in the main of two distinct grades : The one known as linters and the 
other as hull fiber. Depending upon the availability of these differ- 
ent grades, various mixtures of the two are generally used. The ob- 
ject of the bleaching is to reduce the extractive matter to less than 
0.± per cent, and the ash to 0.8 per cent. The presence of chlorides, 
sulphates and lime in amounts larger than traces is likewise objec- 
tionable. If, on the other hand, the cotton is overbleached, a rela- 
tively large amount of cellulose soluble in 10 per cent KoH solution 
is formed. This material, called " soluble cellulose, 7 ' is objectionable 
from the standpoints of nitration, stability, and yield, and the 
amount present in the bleached cotton should not exceed 7 per cent. 
In other words, overbleaching is to be avoided. If uniform nitration 
is to be obtained it is essential that the cotton must be of uniform 
moisture content, of a uniform physical condition, and that it should 
be free from lumps or any extraneous material. 

(a) Picking of cotton. — To obtain this uniformity the cotton is put 
through a picking machine of which there are various forms, e. g., 
the Cogswell Mill, the Cyclone Superior, and the Davis & Furber 
picker. The last-mentioned machine is provided with a toothed 
roller which engages the cotton as it is moved along the feeding 
table, and carries it into such a position that it is caught and torn 
apart by rows of sharp hook-shaped teeth set along six evenly spaced 
elements of a skeleton cylinder revolving at the rate of 1,050 revolu- 
tions per minute. This operation reduces the cotton to a fluffy state 
in which it is caught and blown by air blast into a large flue leading 
into the drying room. 

(b) Drying of cotton. — Two systems of drying are in use: One 
the continuous dryer in which the cotton is conveyed by a belt 
through a long chamber heated to about 100° C, the other by plac- 
ing the cotton in a large chamber which is heated by hot-air blast. 
The former is a continuous operation and the cotton issuing from 
the dryer is weighed directly into metal containers and transferred 
to the nitrating house. The entering cotton usually contains about 
8 per cent moisture. The treatment reduces this to approximately 
0.5 per cent. 



MILITARY EXPLOSIVES. 29 

The chamber system is the more expensive of the two and the 
least desirable from the standpoint of time. These chambers are 
of such a size as to hold approximately 57 bales of cotton or 4,000 
pounds. After the chamber has been filled, it is closed tightly and 
the heat is gradually raised until the temperature reaches 105° C, 
where it is held for 24 hours. After a laboratory test of the cot- 
ton has shown a satisfactory content of moisture, the dried cotton is 
weighed and sent to the nitrating house. 

(c) Nitrating. — In the nitration of cellulose there are two re- 
actions to be considered from the manufacturing standpoint. Al- 
though these reactions occur simultaneously, for the sake of clear- 
ness in description they are to be considered separately — first, the for- 
mation of the nitric acid-ester of cellulose, and the subsequent re- 
moval of the water formed in the reaction by sulphuric acid. 

There are three kinds of acid used in nitrating, namely, fortify- 
ing, fuming sulphuric, and strong-spent acid. The strong-spent acid 
is that which is recovered from the nitrators after nitration has 
been completed. This acid is built up or fortified by use of a forti- 
fying acid, having a strength of approximately 52.35 per cent nitric 
and 44.87 per cent sulphuric. This acid supplies all of the nitric 
acid necessary for the new nitration and a portion of the sulphuric 
acid. The rest of the sulphuric acid is supplied by adding fuming 
acid of 104 per cent H,S0 4 . The main function of the sulphuric acid 
is to combine with the water formed during the reaction, and in this 
manner to prevent the dilution of the nitric acid. In addition to 
this, however, it evidently plays an important part in the actual 
nitration by first converting a part of the substance, in this case cel- 
lulose, either into a sulphuric ester or to a sulphonic acid, which in 
turn is more readily acted upon by the nitric acid. The mixing of these 
acids of different specific gravities has been a subject of a good deal 
of argument on the part of the several large manufacturing com- 
panies concerned. At the present time this mixing is generally ac- 
complished by iron paddles rather than by the use of compressed air. 

Four different systems of nitration have been used in this country, 
viz: The Du Pont mechanical dipper process, the centrifugal process, 
the Thompson displacement system, and the pot process. The rela- 
tive proportions of the nitric acid, sulphuric acid, and water vary 
not only with the different processes, but also with a change in 
weather conditions, more particularly of temperature. The sulphuric 
acid content is maintained very nearly constant, but the variation in 
nitric acid is nearly 1 per cent, and is largely accounted for by the 
fact that a certain amount of denitration of nitro cotton takes place 
during warm weather. Unless the nitric is increased to take care of 
this phenomenon, the resulting nitro cotton will be below speci- 
fications. 



30 MILITAKY EXPLOSIVES. 

1. Du Pont mechanical differ process. — The entire cycle of opera- 
tion in this process is not more than 35 minutes. Under ordinary 
working conditions the fumes are negligible, whereas in all of the 
other nitrating systems the fumes .are always in evidence, so that 
from the standpoint of the health of the operatives the Du Pont 
system is much to be preferred, provided that the proper care is 
always exercised in the manipulation of the machinery. 

A nitrating unit in this system consists of four iron pots so situ- 
ated that they can all be handled from a center point. In each 
nitrator there are two vertical revolving paddles operated in opposite 
directions from each other, the motion being from without inward. 
These paddles consist of a series of horizontal arms so placed upon 
the post that when set in motion the cotton is quickly drawn beneath 
the surface of the acid. A charge of approximately 1,440 pounds 
of acid per nitrator is used, of which the following is a fair average 
composition: HN0 3 , 20.71 per cent; H 2 S0 4 , 62.83 per cent; N,0 4 , 
0.79 per cent; H 2 0, 15.67 per cent. 

When the acid has been run in the paddles are set in motion and 
32 pounds of cotton added. The speed of these paddles varies ac- 
cording to the stage of nitration. At first during the period when 
the cotton is being immersed in the acid the speed is 72 revolutions 
per minute. During the time of nitration, which is usually from 
18 to 24 minutes, the speed is cut to 36 revolutions per minute. 
Finally, when the nitrator is about to be discharged the agitation 
is again as violent as possible, and the speed is raised to that main- 
tained during the immersion process. The bottom discharge pipe is 
then opened and the cotton and acid are let down into a centrifugal 
wringer. 

2. Centrifugal process. — In this system the nitrating and the 
separation of the spent acid from the nitrated cotton are both carried 
on in a large nitrating centrifugal. The latter is filled with a defi- 
nite amount of the mixed acid, usually 50 times the weight of the 
cotton charge, at a temperature of about 32° C, the weighed charge 
of cotton (usually 30 pounds) immersed rapidly by means of an iron 
fork and allowed to stand for about 20 minutes, with occasional turn- 
ing over by means of the fork. The drain cock is then opened and 
the spent acid separated by centrifuging, after which the charge is 
forked out and drowned, as in the mechanical dipper process. 

3. Pot process. — In the pot process the nitration is best carried 
out in iron pots. These are filled with the mixed acid, the cotton 
immersed and allowed to digest for 20 to 30 minutes, when the entire 
contents are dumped into a centrifugal wringer. The pots are moved 
and dumped by means of a suitable two-wheeled truck conveyer. 
The pot process employs considerably less acid than the centrifugal 
process, about 35 parts of acid being sufficient to properly cover the 



MILITARY EXPLOSIVES. 



30a 




Plate 1. — Du Pont Mechanical Dipper Process, Nitrating Floor, Smoke- 
less Powder Factory, Picatinny Arsenal, N. J. 



30b 



MILITARY KXRLOSIVKS. 




Plate 2. — Du Pont Mechanical Dipper Process, Wringing Centrifugal 
Floor, Smokeless Powder Factory, Picatinny Arsenal, N. J. 



MILITARY EXPLOSIVES. 



30<- 




Plate 3. — Du Pont Mechanical Dipper Process, Immersing Basin and 
Exit Flume Floor, Smokeless Powder Factory, Picatinny Arsenal. 
N. J. 

132569—19 3 



30d 



MILITARY EXPLOSIVES. 




Plate 4. — Nitrating Pans, Thompson Displacement Process, Smokeless 
Powder Factory, Picatinny Arsenal, N. J. 



MILITARY EXPLOSIVES. 



31 



cotton. The charge of cotton used is generally about four pounds. 
Sometimes much smaller pots made of earthenware are used, hold- 
ing a charge of only 2 pounds of cotton, several of these charges 
constituting a wringer charge. These small pots are usually emptied 
by hand. 

4. Thompson displacement system. — This process has been em- 
ployed in this country only at Picatinny Arsenal and at present has 
been discarded in favor of the mechanical dipper process. The nitra- 
tion takes place in shallow pans, about 4 feet diameter and 14 inches 
deep, made of heavy earthenware. The cotton (22^ pounds) is 
immersed in 800 pounds of mixed acid at 30° C, mixed thoroughly 
with a fork, and allowed to digest for 1 hour. The charge is then 

SCHEMATIC SKETCH OF UNIT 
OF /V/THATINQ HOUSE. 



fresh mren 



SOUft WATER 




Plate 5. 

covered with a perforated porcelain plate on top of which cold water 
is allowed to run slowly while the spent acid is drawn off at an equal 
rate from the bottom of the pan. There is thus only a slight mixing 
of the water with the upper layers of acid. The spent acid drawn 
off in the first 45 minutes is of sufficient strength to be fortified for 
further use ; that drawn off in the next 10 minutes is " weak spent 
acid," which is sent to the denitrating and concentrating plant for re- 
covery, while the remainder, called " sour water," goes to waste. The 
chief disadvantage of the process is that the slight dilution of the 
spent acid in the zone of contact with the water causes an appreciable 
denitration of the nitro cotton, resulting in nonuniformity of the 
nitrated charge. It is also slower in point of time consumed, but on 
the other hand is more safe from the standpoint of fires. The charge, 
when removed from the pan, is ready for the boiling treatment. 

The object here is to throw the free acid through the basket in the 
shortest possible space of time. Most of the fires which occur in the 



32 MILITARY EXPLOSIVES. 

process are the so-called " wringer fires," and are the result of the 
operatives failing to follow instructions relative to speed of wringer 
and method of discharge. The cotton is wrung for five minutes and 
then discharged into an immersion basin below. As fast as the cotton 
falls into the basin it is submerged by a heavy stream of water dis- 
tributed by a fishtail or some other form which combines the greatest 
dispersion of water with the maximum force for submerging. Fol- 
lowing this the pyro, as it is now called, is transferred by means of 
pumps or by gravity to the boiling tub house. 

The spent acid recovered from the centrifugals is transferred to 
storage tanks to be fortified, as has already been mentioned. Its aver- 
age composition is approximately: HN0 3 , 17.96 per cent; H,S0 4 , 
64.60 per cent ; N 2 4 , 0.67 per cent ; H 2 0, 16.77 per cent. 

The chemical reactions involved in the nitration are not under 
stood definitely, for the reason that the exact molecular weight of 
cellulose is not known. The empirical formula of cellulose is assumed 
to be (C 6 H 10 O 5 ) x , and is thus discussed by Marshall (Explosives, 
Arthur Marshall, Blakiston's, 1917, pp. 135-136) : 

At first the simplest possible formula was assumed for cellulose, CeHioOs, and 
guncotton of high nitrogen content and low solubility in ether-alcohol was sup- 
posed to be formed by the substitution of three N0 2 groups for hydrogen atoms, 
GjHtCMNCMs, and was consequently called trinitro-cellulose. The less nitrated 
product soluble in ether-alcohol was similarly supposed to be the dinitro-cellu- 
lose CsHsCM'NOz);. Later workers obtaining evidence of intermediate stages 
of nitration proposed to increase the formula of cellulose; Eder doubled it, 
Vielle quadrupled it, and Mendeleeff octupled it, giving 48 atoms of carbon to 
each molecule, and hydrogen and oxygen in proportion. A nitro-cellulose hav- 
ing the composition of the above-mentioned trinitro-compound would contain 
14.14 per cent nitrogen. Quite as much as this has never been found by the 
analysis of any product that has ever been obtained, but various investigators 
by nitrating with mixtures of nitric acid and phosphorus pentoxide, or with 
concentrated sulphuric and nitric acids and extracting the product with ether- 
alcohol have obtained percentages between 13.9 and 14.4. Lunge and Bebie 
found that with mixtures of sulphuric and nitric acids the highest percentage 
of nitrogen was attained, not with anhydrous acids, but with mixed acids con- 
taining 11 or 12 per cent of water: with a mixture in which the proportions 
H 2 S0 4 :HNO s :H 2 : were 63.35 : 25.31 : 11.34 they produced a nitro cotton con- 
taining 13.92 per cent N, but this was not stable. After keeping in the wet 
state it was reanalyzed and found to contain then only 13.5 per cent N, and 
other nitro cottons nitrated almost as highly were found to decompose rapidly 
until the same composition was reached, even though the material was kept 
under water. This corresponds very closely with the formula CzJizsCMNCMll, 
endeka-nitro-cellulose. Hence the authors conclude that the molecule with 24 
atoms of carbon fits the facts sufficiently well, but point out that this is only 
the lower limit of the possible size of the cellulose molecule, as to the real mag- 
nitude of which there is little or no evidence. 

With the possible exception of this endeka-nitro-cellulose no definite stages 
of nitration can be recognized ; nitro-celluloses with every percentage of nitro- 
gen from 7 to 13.5 and more can be produced, and those of the same degree of 



MILITARY EXPLOSIVES. 



32a 




Plate 6. — Exterior of Boiling Tub Unit, Old Hickory Smokeless Powder 

Plant, Nashville, Tenn. 



32b 



MILITARY EXPLOSIVES. 




Plate 7. — Interior of Boiling Tub Unit, Old Hickory Smokeless 
Powder Plant, Nashville, Tenn. 



MILITARY EXPLOSIVES. 



32c 




Plate 8.— Jordan Pulping Engine Unit, Old Hickory Smokeless Powder 

Plant, Nashville, Tenn. 



:i2d 



MILITARY EXPLOSIVES. 




Plate 9. — Jordan Pulping Engine Unit, Old Hickory Smokeless Powder 

Plant, Nashville, Tenn. 



MILITARY EXPLOSIVES. 



33 



nitration may be soluble to very different extents in ether-alcohol. To char- 
acterize a nitro cotton it is better to specify the percentage of nitrogen and the 
solubility rather than to state the number of N0 2 groups that it is supposed to 
contain in each molecule. The following table shows the percentage of nitrogen 
and the volume of gas evolved in the nitrometer by the different nitro-celluloses 
of the C 2 4 series. The figures have been calculated, using the latest atomic 
weights. 



Designation. 


Formula. 


c.c. NO 
per lg. 


Per cent 

N. 


Dodeka-nitro-cellulose. 


Co 4 H2802o(N02)12 


225.6 
215.0 
203.5 
190.9 
177.3 
162.4 
146.0 
127.9 
107.9 


14.14 


Endeka-nitro-cellulose. 


Ca4H»Ojo(NOj)ll 


13.48 


Deka-nitro-cellulose 


C 2 4H3oO M (N0 2 )10 


12.76 


Ennea-nitrocellulose 


024H 31 O20(NO 2 )9 


11.97 


Okto-nitro-cellulose 


C 2 4H32O20(NO S )8 


11.12 


Hepto-nitro-cellulose 


Co 4 H3302o(NC>2)7 


10.18 


Hexa-nitro-cellulose 


C24H 3 4O20(NO 2 )6 


9.15 


Penta-nitro-cellulose 


OmHsjOjoCNOj^ 


8.02 


Tetra-nitro-cellulose 


CH^CW NCM4 


6.77 


I 





Escales (Die Explosivstoffe mit besondere berucksichtignung der 
Neuren Patente, Bearbitet von, Dr. Richard Escales, Leipzig, von 
Veit, 1914) discusses the cellulose nitrate from a slightly different 
standpoint, as shown by the appended table. 



Composition of cellulose (nitrated). 



Parts 
nitrate. 


Designation. 


Formula. 


c.c. NO 
per lg. 


Per cent 

N. 


12 


Dodeka-nitro-cellulose 


Co4H"80 8 (N0 3 )12 


226. 27 
215.17 
203. 35 
190. 75 
177. 19 
162.36 
145.96 
127.91 
107. 81 


14.14 


11 


Endeka-nitro-cellulose. . . .. . 


Co4H S 90 9 (N03)ll 


13.47 


10 


Deka-nitro-cellulose 


C 2< H3oOio(N0 3 )10 


12.75 


9 


Ennea-nitro-cellulose. . 


C 2 «H 31 On(N0 3 )9 


11.96 


8 


Okto-nitro-cellulose . .... 


C 2 4H3 2 0i 2 (N0 3 )8 


11.11 


7 


Hepto-nitro-cellulose 


C 2 4H 33 Oi 3 (N0 3 )7 


10.18 


6 


Hexa-nitro-cellulose . 


C»4H 3 40i 4 (N0 3 )6 


9.15 


5 


Penta-nitro-cellulose . . . 


C 2 4H 35 15 (N0 3 )5 


8.02 


4 


Totra-nitro-cellulose. . . 


Co 4 H 36 O n (N03)4 


6.76 











It should be definitely understood that nitrocellulose is not a true 
nitro body, but is a nitric-acid-ester, or nitrate of cellulose. Nitrates 
yield all their nitrogen as nitric oxide (NO) in the nitrometer; nitro 
bodies do not. Hence the term "nitrocellulose" is also a misnomer, 
but has become standard through long usage. The same remarks 
apply to nitroglycerin and nitrostarch. 

In the nitration of the cotton there are two things to be accom- 
plished: First, the formation of a product containing a high per- 
centage of nitrogen; and second, the formation of a product which 
will be 99 per cent soluble in a mixture of two parts ether and one 
part alcohol. A correctly prepared pyro should contain 12.60 per 
cent N±0.1 per cent, and corresponds very closely to the deka- 
nitrocellulose. The solubility phase is very important for the 
reason that the nitro cotton is eventually converted into a dense 



34 MILITARY EXPLOSIVES. 

colloid, the properties of which depend upon the solubility of the 
nitrocellulose. If this colloid is of low solubility the resulting gran- 
ulation will lack in uniform consistency, due to the fact that there 
will be white particles of uncolloided cotton throughout the mass. 

(d) Purification. — Under the general term of purification is in- 
cluded the following sequence of processes: Preliminary boiling, 
pulping, poaching, screening, and wringing. It is impossible with 
our present limited knowledge of the cellulose molecule and of the 
intermediate reactions occurring during the nitration of the molecule, 
to control the reaction to such an extent that a nitrocellulose, con- 
sisting of but one nitro body, will result from a certain reaction 
accomplished under a set of standard conditions. The products of 
the reaction always include certain of the lower nitrocelluloses. 
These bodies influence the stability of the whole mass and must, 
therefore, be removed before the stability of the pyro cotton can be 
guaranteed. The object then of the purification treatment given to 
the pyro is to insure a uniform stability by eliminating, through 
hydrolysis or other means, these unstable lower nitro bodies. This 
is accomplished most easily by prolonged boiling in water, which in 
the preliminary treatment has an acidity varying from 0.1 to 
0.3 per cent calculated at H 2 S0 4 . 

The preliminary boiling process is carried out in large wooden 
tubs, constructed preferably of cypress and having a false bottom. 
Underneath this false bottom is a system of steam pipes which pro- 
vide the means of bringing the contents of the tub to the boiling 
point. The tubs hold about 1,200 pounds of pyro cotton. After 
charging a tub with cotton cold water is run in until the cotton is 
entirely submerged. The steam is then turned on and the contents 
of the tub boiled for 16 hours. During this process it is necessary to 
add additional water from time to time so that none of the cotton 
becomes exposed to air. The actual boiling time must be 16 hours. 
The steam is then turned off, the tub refilled and boiled again for 8 
hours. This is repeated until each tub has had a 40-hour boil, with 
not less than four changes of water. Careful attention to the details 
in the boiling-tub house insure to the finished pyro cotton a higher 
ether-alcohol solubility and a more satisfactory stability than one 
in which these details have been disregarded. 

Pulping. — The next process, that of pulping, has for its object the 
reduction of the cotton fibers to a uniform state of division so that 
subsequent formation of a colloid by means of the ether and alcohol 
mixture will be entirely uniform. The degree of fineness is determined 
by laboratory test and has been the subject of a great deal of discus- 
sion. It has been maintained by some manufacturers that a finely 
cut pyro produces a powder inferior in toughness to that made from a 



MILITARY EXPLOSIVES. 



34a 




Plate 10. — Miller-Duplex Type Beater, Smokeless Powder Factory, 

Picatinny Arsenal, N. J. 



34b 



M1L1TAKY EXFLOSIVES. 




Plate 11. — Interior of Poaching House, Old Hickory Smokeless 
Powder Plant, Nashville, Tenn. 



MILITARY EXPLOSIVES. 35 

coarser cut pyro, but since the colloiding operation tends to destroy 
the fibrous condition of the cotton, it does not appear to be altogether 
reasonable to assume that the degree of fineness of pyro has an 
appreciable effect upon the toughness of the finished powder. The 
pulping operation is accomplished by machines similar to those used 
in the paper industry. 

The most efficient means for pulping cotton is provided by the 
Jordan machine. This is operated on the centrifugal principle, by 
means of which the entering cotton is thrown from the large end of 
the beater to the small tapered end, and from thence to a storage 
tank over the machine. The more efficient way of running these units 
is to have them adjusted in such a manner that the cotton is given a 
progressive cut. In other words, the first Jordan machine will give 
only a fairly coarse cut to the cotton, the next a little finer, and so on, 
until the cotton has finally been pulped to the necessary degree of 
fineness. 

The other types of machines used for this purpose are either the 
Jordan beater or the Miller duplex beater. The essential features of 
a pulping machine consist of a fixed set of knives at the bottom of 
a tub over which revolves a roller which is mounted in adjustable 
bearings and carries a removable set of knives. The pulping is ac- 
complished by the rolls repeatedly drawing the pyro cotton between 
the two sets of knives and thus reducing the material to any desired 
degree of fineness. A weak soda solution is used during this process 
for the purpose of neutralizing the acid retained within the fibers of 
the cotton and which is set free mechanically when these fibers are 
macerated. 

With the Miller duplex beater the hull fiber is cut in a much 
shorter time than the linters, the variation being between six and 
eight hours per beater lot. During the first stage of the pulping 
treatment, a washer, consisting of a large octagonal box covered with 
very fine wire screen, is lowered into the pulp to remove a part of 
the sour water, fresh water being added at the same time. The 
water thus removed passes to settling basins where any pyro carried 
off mechanically is recovered. When the desired degree of fineness 
lias been obtained, the material is ready for the next purifying 
process. 

Poaching. — It has already been pointed out that in the pulping 
operation the fibers of the cotton are broken down mechanically so 
that the original physical texture of the cotton is destroyed. The 
preliminary boiling tub treatment reduced the acidity of the fibers 
and of the interstitial material, but the pulping process, by macerat- 
ing these fibers, has set free an additional amount of acid. It is. 
therefore, necessary to repurify the cotton by boiling. This opera- 



36 MILITARY EXPLOSIVES. 

tion is carried on in the poacher house in a manner somewhat similar 
to that described in the boiling tub house, but with the notable differ- 
ence that the first boiling treatment is carried out in an alkaline so- 
lution. For this purpose there is dissolved 1 pound of sodium 
carbonate (soda ash) to a gallon of water, and for every 2,000 
pounds of dry nitrocellulose there may be added 10 gallons of 
this solution. It is necessary to repeat the boiling operation five 
times, but the soda is only added during the first boiling. All the 
other treatments are made in a neutral solution. During all of these 
treatments a thorough agitation of the cotton is essential so that it is 
necessary to employ mechanical stirrers driven by gears and shaft- 
ing. At this stage of the operation it is necessary for the chemical 
laboratory to determine: (a) The stability of the cotton by K. I. 
test and 135° test, (b) the percentage of nitrogen in the cotton, 
(c) the solubility of the cotton in the ether-alcohol mixture, (d) the 
degree of fineness, and (e) the ash. The details of performing these 
analyses are described in another chapter. 

After purifying the pyro-cotton, as described above, it is neces- 
sary to separate mechanically any foreign material or any portions of 
the cotton which may not have been properly macerated in the 
beater house. This is accomplished by means of the Packer pulping 
screen. This piece of machinery consists of a large box, the bottom 
of which is fitted with a brass plate having slits one one-hundreth 
inch in width. The cotton is drawn through these slits by suction 
underneath the screen and any particles which are too coarse to pass 
through are returned to the beater house for additional treatment. 
From the Packer screen the cotton is pumped into one of the 
large blending tubs where it is stored until needed in the next opera- 
tion. 

Wringing. — The transference of the cotton from the time of nitra- 
tion up to this stage of manufacture is accomplished by having the 
cotton suspended in water. It is the function of the wringers to re- 
move all of the excess water from the cotton so that the subsequent 
operation of dehydrating by means of alcohol will be done with the 
minimum amount of water present. This wringing operation con- 
sists merely in forcing the water out of the cotton by means of cen- 
trifugal action. 

The wringer consists of a wire basket of such a mesh that the cotton 
is held within the screen. This basket is connected by means of a 
shaft to a motor, and is so geared that the basket revolves at a speed 
of 800 revolutions per minute. This centrifugal action forces the 
water out of the cotton through the basket and so on down the drain 
pipe. At the end of this operation another sample is sent to the 
laboratory for the purpose of determining the amount of moisture 



MILITARY EXPLOSIVES. 



36a 




Plate 13. — Operating Floor, Dehydrating Press House, Smokeless 
Powder Factory, Picatinny Arsenal, N. J. 



MILITARY EXPLOSIVES. 



37 



remaining in the cotton. This should average between 28 and 30 
per cent. It is necessary to maintain the moisture at this figure in 
order to insure safety from the standpoint of fire. 

If the wringers are operated at a uniform rate of speed for the 
same length of time the moisture content will not vary more than 
2 per rent. This operation concludes the manufacture of pyro cotton 

SCHEMATC SKETCH OF 
PACKER PULP SCREEN. 



SCREEN 

plate mrs 




SCREEN PLATE 
TYPE A. 



O/APHRAGM 
RUBBER AND COTTON DUCK 



SPRINGS AND LEVER DEVICE FOR 
MAINTAINING TENSION ON SNOE 
HENCE ASSURING MOVEMENT OF 
DIAPHRAGM . 




DIAPHRAGM MOVES 
VERTICALLY ABOUT 
% PER STROKE 



-^PLUNGER 
CAST IRON 



HARD MAPLE 
SHOE 



CAMS 



CAM SHAFT 



Plate 12. 



and the material from this time on loses its identity as such and is 
called, for the want of a better word, the "colloid" or the "powder." 
Dehydration, — The pyro from the wringers, containing approxi- 
mately 30 per cent moisture, is transferred to storage and placed in 
warehouses to prevent freezing in winter time until it is required for 
dehydration. The object of this operation is to remove all of the water 
from the pyro and to add in its place the quantity of alcohol neces- 
sary to form the colloid. This amount varies within relatively small 
limits and is dependent upon the solubility of the pyro being used, 
as shown by laboratory tests, and also, to a certain extent, upon the 
132569—19 4 



38 



MILITARY EXPLOSIVES. 



size of granulation of the final powder. It is customary to add 1£ 
pounds of alcohol for every pound, dry weight, of cotton. 



SCHEMATIC SKETCH OF 
'DEHYDRATING SYSTEM. 



r^ 



GLASS 



COMPRESSED 
AIFI ~^ 



( 




EXHAUST 

W SPENT 

ALCOHOL 

TANK 



\ NEW 
ALCOHOL 



a 



TO DEHYDRAT- 
ING PRESS 



il 




^^ 



i 



2^ 



1 ZZZZZZZZZZZZZ& 



£ 



70 SPENT ALCOHOL 
TANK 



*PftOM PRESSURE LINES 

Plate 14. 
The amount of solvent (ether-alcohol) necessary to form the col- 
loid is determined from previous experience of manufacture and is 
correlated with ballistic data obtained from the proving ground. For 
certain types of gun it has been found that 100 per cent solvent (67 



MILITARY EXPLOSIVES. 



38a 




Plate 15.— Large Dehydrating Press, Smokeless Powder Factory. 

Picatinny Arsenal, N. J. 



MILITARY EXPLOSIVES. 39 

per cent ether and 33 per cent alcohol) produces a colloid which will 
give the most uniform results from the standpoint of graining and 
also from the standpoint of firing. In the event that 100 per cent 
solvent is to be used or 1 pound of solvent for every pound of pyro, 
it will be necessary that the original block of 25 pounds dry weight 
of pyro be increased to 33 pounds 4 ounces. 

The dehydrating operation is conducted somewhat as follows: 
The press consists of a cylinder and movable piston operated by 
hydraulic pressure, as indicated on the attached sketch. The 
press is charged with pyro and "low pressure" (about 1,200 pounds 
per square inch) is applied for a few moments, thus squeezing out 
a portion of the excess water in the cotton. The predetermined 
amount of alcohol is then forced into the press by use of a pump, 
and the pressure then increased to about 3,700 pounds per square 
inch. The alcohol functions first as a displacing agent and finally 
as a dehydrating agent. Its initial entrance into the block forces out 
a small portion of the remaining water ; later, however, it combines 
with the residual water and produces a block of pyro nearly free 
of water. The first portion of this alcohol contains relatively large 
amounts of water and is forced out of the press into the spent alcohol 
tank. The remaining amount, however, is nearly 90 per cent alcohol. 
The spent alcohol resulting from this process is pumped back into 
the storage tank and eventually sent to the ether still for the manu- 
facture of pure ether. 

The subject of changing the point of exit of the spent alcohol 
from the bottom of the block to the top of the block has been dis- 
cussed by some of the manufacturing companies and is in fact in 
operation by certain plants. This change in method is technically 
known as the " full back up " system of dehydrating as differen- 
tiated from the " no back up " system. Proponents of this new sys- 
tem claim that the residual alcohol remaining in the dehydrated 
block contains a smaller percentage of water than alcohol remaining 
in a block which was dehydrated by the " no back up " system. The 
claim is also made that dehydration is more uniform throughout 
the block. So far no figures have been submitted to prove these two 
statements. It may be said, however, that the production is in- 
creased to a considerable extent by the use of this system, this in- 
crease being made at the expense of the quality of the product 
obtained. The effectiveness of the system depends entirely upon 
the care which is exercised by the operator and since a part of the 
technique of this new method consists in holding the alcohol for a 
definite time in the block, there would always be a tendency on the 
part of the operator to shorten this period of time with the conse- 
quent result of slurring the operation and of turning out an inferior 
block. 



40 MILITARY EXPLOSIVES. 

The dehydrated blocks must be first thoroughly broken up before 
the next operation of mixing is commenced. For this purpose they 
are transferred into a rotating drum or block breaker, equipped on 
the inside with a wire screen and iron prongs. This barrel upon 
revolving throws the block against the prongs, thus breaking it 
into small lumps which lend themselves more readily to the mixing 
operation and which in turn insures a more even colloid. 

From this point up to the time the powder is put into the solvent 
recovery the powder is kept in closed containers as much as possible 
between the various steps in the manufacturing process in order to pre- 
vent excessive losses in solvent, which is an important point, not only 
from the economical but also from the manufacturing standpoint. 

Mixing. — The mixing operation is the second step in the forma- 
tion of the colloid. As has been pointed out above, unless care is 
exercised during the dehydrating process in producing a block of 
uniform dehydration, it will be impossible to secure a good colloid. 
It is no less important that the ether be added to the mass in such 
a manner that the evaporating losses are minimized by incorporat- 
ing the ether throughout the mass as quickly as possible. This is 
accomplished by the use of a mixing machine. It consists of a 
covered brine-cooled tank in which a double worm revolves, giving a 
kneading motion to the material in the mixer. With this worm in 
motion, the ether is added through a distributing plate in such a 
way that the evaporative losses are reduced to a minimum, but at 
the same time it is not added fast enough to jeopardize a proper 
mixing. In the case of the small arms powders and of the one 
pounder single perforated grains, graphite is added to the mixer 
charge before the ether is run in, and it is sometimes the practice 
to set aside one set of mixers for graphited powders. 

It is also at this stage of the process that the so-called stabilizer 
is incorporated into the colloid. The material used for this purpose 
is diphenylamine, and there is dissolved in the ether enough of this 
substance so that the finished powder will contain between 0.40 and 
0.50 per cent diphenylamine. 

The object of adding diphenylamine at this stage is to thoroughly 
incorporate it throughout the colloid so that on long continued 
storage any nitrous fumes which may be evolved from the powder 
will be absorbed by this so-called stabilizer. The many factors 
entering into the use of this material are more properly discussed in 
a later chapter on surveillance and stability. 

Pressing. — The colloid is next subjected in sequence to the action 
of a preliminary press, a macaroni press, 1 and a final blocking press. 

1 Since the writing of the above, the use of the macaroni press has been abandoned, the 
same object being accomplished now at all plants by means of one or more 10-20 mesh 
steel wire plates inserted in the graining press between the 35 powder Mock and the die 
plate. 



MILITARY EXPLOSIVES. 



40a 




Plate 16. 



Ob 



M1LI1 AltY EXPLOSIVES. 




Plate 17. 



MILITARY EXPLOSIVES. 



40c 




Plate 18. 



40d 



MILITARY EXPLOSIVES. 




Pt-atf. 19. 



MILITARY EXPLOSIVES. 41 

The incorporation of ingredients as accomplished in the mixing is 
really but a preparatory stage for the final formation of the colloid, 
this last step being completed by the action of the presses. 

The preliminary blocking press consists merely of a cylinder and 
piston similar in action to the dehydrating press. It forms the col- 
loid into a dense cylindrical mass by subjecting it to a compression 
of 1,800 pounds per square inch. This " preliminary block," so called, 
is then transferred to the macaroni press. The operation here con- 
sists in straining the solid block of colloided matter through a heavy 
brass screen and at a pressure of 4,800 pounds per square inch, in 
such a manner that the material as it is ejected is similar in appear- 
ance and size to macaroni. As it leaves this press it falls by gravity 
into the hopper of the final blocking press. This is similar in every 
respect to the preliminary blocking press and forms the colloid into 
the final shape before it is taken to the graining press. The block is 
here subjected again to heavy pressure for exactly three minutes, 
thus completing the colloiding of the pyro cotton. The colloid now 
is entirely different in appearance from the material as drawn from 
the mixers, for it has been changed from a mass resembling damp 
sawdust to a dense, elastic, dark brown substance. These operations 
of pressing insure, to the greatest possible degree, a uniformly 
thorough action of the solvent upon the pyro, and very nearly elimi- 
nate the possibility of having uncolloided cotton in the finished 
powder. 

Graining and cutting. — The final operation from the standpoint 
of the granulation of the powder occurs in the graining press room. 
These presses may be set either horizontally or vertically. Their 
action is to force the colloid through a steel die, shown in accom- 
panying figure, in such a manner that the expressed material, which 
takes the form of a string, will be delivered at a uniform rate of 
speed under the control of the operator at the press. The power 
which is necessary to force this colloid through the die is very great 
and is supplied by means of a hydraulic ram, under a pressure of 
2,500 to 3,800 pounds. The press head may be equipped with one or 
more barrels, depending upon the rate of production of the colloid 
from the other departments and also upon the capacity of the grain- 
ing presses themselves. When small arms powder is being grained 
there may be 50 strings issuing simultaneously from the head. With 
a large caliber powder, however, such as 16-inch gun, it is customary 
to use but one barrel, or at the most two. The " powder " issues from 
the press head in the form of a flexible rope which is led over pul- 
leys to a cutting machine. This cutting machine is capable of very 
fine adjustment and is so manipulated that the ratio of the diameter 
of a grain to its length always remains constant. 



42 MILITARY EXPLOSIVES. 

The factors affecting the size of the grain and its relation to the 
type of gun for which it is designed are discussed in a subsequent 
chapter. 

Solvent recovery. — Having prepared the powder in a definite 
form of granulation the next step is that of recovery of the ether 
and alcohol which is given off during the process of drying. The 
unit which is concerned in the recover}' of this solvent is termed the 
solvent recovery, and may consist of any one of three types: First, 
the chamber type of solvent recovery, in which the powder is trans- 
ferred from a car to a small galvanized iron box set in an air-tight 
chamber; second, the car type of solvent recovery, in which the car 
itself containing the powder grains becomes the chamber: and third, 
the can type of solvent recoveiw. In all of these the governing 
principle is the same. 

Warm air is circulated through the powder and is then forced over 
cold coils. This change in temperature causes a precipitation of the 
solvent upon the coils and produces, in effect, a miniature fog. The 
saturated air after passing over these cold coils loses its surplus 
solvent, is reheated and then is again forced through the powder 
in continuous cycle, in this manner completing the closed system 
of ventilation. The length of treatment depends upon the size of 
the powder ; the larger calibers, of course, requiring a greater length 
of time than the smaller ones. Definite rules are laid down govern- 
ing the length of time necessary for powder to remain in the solvent 
recovery building — rules which are the result of experiments and 
which combine the maximum of efficiency with the best results from 
the standpoint of drying. 

Drying. — There are three separate types of drying operations: 
The first and most satisfactory, except from the standpoint of time, 
is the air dry. A second method, known as the water dry system, has 
a great advantage as to time saving, and up to the present time there 
is little reason to believe that the resulting powder is not as satis- 
factory as that dried by the air method. Finally, a new process, 
termed the Nash alcohol dry system, appears at the present time 
to have unlimited possibilities from all standpoints. It is also the 
more logical from the chemical standpoint, for the main difficulty 
in the drying of smokeless powder consists in the elimination of 
the ether rather than the alcohol from the colloid. This is more 
readily accomplished by alcohol than by either water or air, as used 
in the first two methods. 

Air dry treatment. — In this treatment the powder is transferred 
directly from the solvent recovery house to the dry house and placed 
in bulk in large bins. The temperature is raised after a time and 
maintained as high as 45° C. These bins are narrow, so as to give 



M 1LITAHY EXPLOSIVES. 



42a 




Plate 20. — Charging Floor, Can Type, Solvent Recovery House, 
Smokeless Powder Factory, Picatinny Arsenal, N. J. 



421) 



MILITARY EXPLOSIVES. 




Plate 21. — Can and Discharge Floor, Can Type, Solvent Recovery 
House, Smokeless Powder Factory, Picatinny Arsenal, N. J. 



MILITAEY EXPLOSIVES. 



43 



a relatively thin cross section, to insure an even distribution of heat 
throughout the mass of powder. From time to time the laboratory 
analyzes a sample of the powder to determine if the required mois- 
ture and volatile content has been reached. This moisture and vola- 

SCHEMATIC SKETCH OF 
NO'S. 3 AND 5 DRYHOUSES. 

CIRCULATION. 




AIR INLET 



wire: 



ARROWS SHOW COURSE OF 
AIR CIRCULATION. 

Plate 22. 

tile content, or total volatiles, as it is sometimes called, is very im- 
portant from the standpoint of ballistics. 

Smokeless powder is, to a certain extent, hygroscopic. Extensive 
experiments have been performed for many years to determine defi- 
nitely the amount of total volatiles necessary in a certain size powder 
to give the best results. If the powder is permitted to become too 
dry, a small weight of charge with correspondingly large air space 
will be encountered in the test firings in the gun, resulting in ex- 



44 MILITARY EXPLOSIVES. 

cessive pressure at service muzzle velocity, owing - to too rapid com- 
bustion. If, on the other hand, it is not dry enough a relatively 
high weight of charge with correspondingly small air space will 
result in excessive pressure at service muzzle velocity. It is, then, 
very necessary that the drying operation be carefully watched from 
the standpoints of chemical control and of technical manipulation 
of the house. 

Water dry treatment. — The main difference between the air dry 
process and the water dry process is the difference in the surround- 
ing medium. In the first case it is warm air, and in the second warm 
water, but the object desired is the same in either case. Water is 
kept circulating throughout the powder at temperatures which are 
at first relatively low, but which are subsequently raised to 55° C. 
Later the powder is removed and air dried for a short time; this 
latter treatment requiring much less time to finish than when the 
powder has only the air dry treatment. 

A later development in this process is the so-called " continuous 
drier." This differs from the ordinary dry house treatment in that 
the drying of the powder is accomplished in between 4 and 5 hours, 
depending upon the size of the granulation. The powder enters the 
dry house from the water dry system, is hoisted to a hopper and 
then slides by gravity into a shaking screen. This screen removes 
foreign material, and drops the powder to a bucket conveyor of the 
ordinary type. The powder is then hoisted to the top of the building, 
where it is thrown into a drying chute. This chute is approximately 
6 inches in thickness, 5 feet in width, and about 10 feet in length, 
and is equipped with baffles running crosswise in the direction of its 
smallest dimension. A series of screens on the side wall provide 
the means for the passage of warm air through the powder; and a 
temperature of 50° C. is maintained by this means at the bottom of 
the chute. A shaking device near the floor is capable of such regula- 
tion that the rate of discharge from the drier, and consequently the 
volatile content of the powder, is controlled by the speed at which this 
shaker is operated and by the amount of clearance between the shaker 
and the bottom of the chute. In one of the largest plants one con- 
tinuous drier is capable of drying to the correct moisture and vola- 
tile content 100,000 pounds of 75 mm. powder in 24 hours. 

Alcohol dry treatment. — In the Nash alcohol dry system the drying 
medium is a mixture of water and alcohol. The relative percentage 
of the two liquids varies according to the caliber of the powders, 
and experimental work is still being carried out to determine the best 
working conditions. If too strong an alcohol is used, it results in a 
brittle powder, a powder in which the external moisture is reduced to 
a very small amount, and one in which the shrinkage alters to a con- 
siderable extent the web dimensions. ■ This naturally gives excessive 



MILITARY EXPLOSLVES. 



44a 




Plate 23. — Exterior op "Continuous" Process Dry House, Old Hickory 
Powder Plant, Nashville, Tenn. 

132569—19 5 



44b 



M1L1TAKY EXPLOSIVES. 




Plate 24. — Interior of "Continuous" Process Dry House, Old Hickory 
Smokeless Powder Plant, Nashville, Tenn. 



M 1LITAKY KXPLOS1YKS. 



44c 




Plate 25.— Cannon Powder Blender, Old Hickory Smokeless Powder 

Plant, Nashville, Texx. 



MILITARY EXPLOSIVES. 45 

pressure in the gun. If too weak an alcohol is used, the time of dry- 
ing is proportionately lengthened. This alcohol dry system has the 
advantage, that none of the ether is lost and but a very small part of 
the alcohol. It also does away with the solvent recovery treatment 
and it is only necessary to put the powder in the air-dry house for a 
short space of time to obtain the correct percentage of total volatiles, 
or to finish with a water-dry treatment and final drying in the con- 
tinuous drier. 

Blending. — The next step and perhaps the most important one 
from the standpoint of uniformity of firing is the proper mixing or 
blending of a certain arbitrary amount of powder. For the larger 
caliber guns it is customary to blend or mix either 50,000 or 100,000 
pounds of powder, but for the smaller caliber powders, particularly 
for the small arms powders, lots ranging from 15,000 to 50,000 
pounds are more usual. The blending operation consists merely in 
the transference of the powder by means of gravity from one bin to 
another bin, this transference resulting in a thorough mixing of all 
of the lot. These bins are so constructed that when full of a lot of 
powder the powder assumes the shape of a double cone with one apex 
pointed down toward the discharge pipe and the other apex pointed 
up toward the top of the bin. The proper construction of these bins 
from the standpoint of the correctness of the angles at the sides of 
the bin is very important. If the sides of the bin are too steep the 
powder will slide down toward the apex of the lower cone. If, on 
the other hand, the sides are built on too gradual a slope the powder 
will not flow freely from the bin and it would be necessary to use a 
raking device in order to empty the bin toward the end of the lot. 
It is essential, therefore, that a point midway between these two be 
found, a point so selected that the powder will not slide down the 
side of the bin, yet at the same time will insure a complete empty- 
ing and mixing of the lot. These angles have been determined and 
when the principles are observed no difficulty results from lack of 
proper blending. After two or three cycles from one bin to the 
other have been completed, the powder is weighed and boxed. 

A new type of blender has been worked out at Picatinny Arsenal, 
which apparently is a considerable improvement over the old 
" tower blender." In the place of two bins set one upon the other 
as in the old type, an awkward arrangement which necessitated a 
building at least 100 feet high, two separate buildings were con- 
structed about 100 feet apart. The bottom of the one bin is con- 
nected with the top of the other by an endless belt. There are, 
then, two belts operated independently of each other for the trans- 
ference of the powder from the bottom of one bin to the top of the 
other. The arrangement at the bottom of each bin is such that the 
powder may be boxed in either building. When it is desired to 



46 MILITARY EXPLOSIVES. 

empty one bin and transfer to the other for the purpose of blending^ 
it is merely necessary to put the belt in motion and open the chute. 

The speed of the belt is such that 100,000 pounds are hoisted in 40 
minutes, a speed not possible with the older type of blender. This 
blender requires but one man to operate, whereas with the other 
type it was necessary to have about 10 men. The fire risk also is 
reduced to a minimum, for in case one building should take fire, 
a series of water curtains within the shed over the belts would con- 
fine the blaze to its point of origin. 

After the blending is completed the lot of powder is boxed and 
stored. The powder container used for storage is merely an air- 
tight zinc box about which is built a wooden box completely cover- 
ing and protecting the metal inside. It is of such a size as to hold 
from 110 to 140 pounds of smokeless powder, depending upon the 
type of box. These boxes are tested for air leaks to insure the 
powder retaining the same moisture and volatile content as when 
withdrawn from the dry house. 



MIUTAHY EXPLOSIVES. 



46a 




Plate 26. — Cannon Powder Blender, Smokeless Powder Factory, 

Picatinny Arsenal, N. J. 



46b 



MILITARY EXPLOSIVES. 




Plate 27. 



MILITARY EXPLOSIVES. 



46c 




Plate 28.— Box Filling and Weighing Floor, Cannon Powder Blender, 
Smokeless Powder Factory, Picatinny Arsenal, N. J. 



46d 



MILITARY EXPLOSIVES. 




Plate 29. — Powder Box Testing House, Smokeless Powder Factory, 

Picatinny Arsenal, N. J. 



CHAPTER II. 

' ' \ ■ i ' 

GRANULATION OF SMOKELESS POWDEK. 

GENERAL. 

The propellant used as a charge for the gun possesses a certain 
force or latent power which upon combustion becomes a kinetic or 
moving force and which drives the shot to the muzzle of the gun. 
That which actually occurs when powder is ignited is as follows: 
In the first place, the powder is converted by change of state, i. e., 
from solid to gas, into a volume greater than that originally occupied 
by the powder; in the second place, the heat generated by the ex- 
plosion expands the volume of this gas and increases its pressure. 
Since the pressure of the gas is equal in all directions, the expansion 
will naturally follow the line of least resistance, thus setting the 
projectile in motion. 

The rapid development of the gas pressure within the gun should 
be of such a progressive nature that the force exerted should not 
attain its maximum at the time of the ignition (as would be the case 
if a high explosive were used as a propellant), but rather should 
attain it by a relatively gradual rise. The control of this pressure 
lies in the form of granulation of the individual powder grains. 
This granulation determines the area of the burning surface of the 
grain, which in turn controls rate of combustion, and through that, 
the pressure. 

A brief consideration of the factors influencing and determining 
the proper granulation of the powder will involve a discussion, first, 
of the best form of the powder grains, and second, the factors which 
influence the size of the grains. 

The best form of granulation from a ballistic point of view is, 
first, that which with the smallest given weight of charge will im- 
part to the projectile the highest muzzle velocity within the pre- 
scribed limits of maximum pressure ; second, that which will cause the 
minimum erosion to the bore, and third, that which shows maximum 
regularity in ballistics. The grains should burn uniformly from 
the surface and the rate of burning should vary directly with the 
pressure; the greater the burning surface, the higher the pressure, 
other things being equal. It is evident, therefore, that the shape of 
the grain is a direct factor in determining the amount of burning 
surface. 

Shape of granulation. — When the powder is ignited its rate of 
burning is dependent upon the area of the burning surface. It was 
formerly supposed ^hat the powder grains should be so designed 

47 



48 MILITAKY EXPLOSIVES. 

that this area should remain nearly constant, in an attempt to main- 
tain the original pressure developed upon ignition throughout the 
period of combustion. 

Powder was made in the form of tubes, broad tapes, and thin 
flakes as the result of efforts to realize this condition. This theory, 
however, is not in accord with the practice in this country, and it 
has been demonstrated that instead of maintaining a constant pres- 
sure during the combustion of the charge, the pressure should be 
gradually increased until the maximum is reached, in the case of the 
ideal gun, at the time that the projectile is about to leave the muzzle. 
Our guns are designed to withstand a pressure increasing to the 
maximum at a point in the bore just ahead of the powder chamber. 
If this object is to be attained there must be an actual progressive 
increase in the area of the burning surface. This larger area may 
be secured either by altering the shape of the grain (for example, 
from a true cylinder to a square form, or better, to the Walsh grain), 
or else by perforating the grain longitudinally, with holes so spaced 
that the progressive burning of the grain increases the area exposed 
to ignition. This multiperforated grain has been manufactured in 
three shapes, namely, the cylindrical grain, the square grain, and, 
lastly, the sliverless or Walsh grain. Of these three, however, the 
cylindrical form has been the most used. The cylindrical or multi- 
perforated grain for cannon powder has seven circular longi- 
tudinal perforations, one central and the other six equally dis- 
tributed midway between the center of the grain and its cir- 
cumference. A uniform distance between the center of the central 
perforation, the center of the outside perforation, and the outside 
circumference of the grain itself is the object sought, since it has 
been found that this facilitates the complete combustion of the 
charge. The length of the dry grain is between 2.1 and 2.5 times the 
outside diameter. For the smaller type of gun the multiperforated 
grain finds no use, and in its place the single perforated grain has 
been adopted. The types of gun for which the single perforated 
grain is used are the .30 caliber rifle, 37-mm. gun, 2.95-inch sub- 
caliber, 2.95-inch mountain gun, and 3-inch mountain howitzer. Un- 
like the multiperforated grain, it burns with practically a constant 
burning surface. 

The square form of grain is made with four longitudinal ridges on 
each side and nine square perforations. Contrary to expectations, 
this grain has not proved satisfactory, first, because of the difficul- 
ties in cutting the die, and, second, because of the difficulties in main- 
taining the square shape of the grain, due to the soft, pliable nature 
of the colloid. 

Another form of grain, the sliverless or Walsh grain, was invented 
by Col. J. E. Walsh in 1912, at Picatinny Arsenal. The following 



MILITARY EXPLOSIVES. 



49 



diagram shows a comparison of the burning surface of the cylindrical 
and sliverless grains. When the cylindrical grain is burned it can 
be seen that there still remains to be burned six inner and six outer 
pieces of powder of triangular cross-section called slivers. The 
Walsh or sliverless grain eliminates this defect, leaving no slivers 
when the powder in the charge is burned. This complete combus- 
tion of each grain of powder has a direct economic effect in that it 
reduces the weight of the charge, and also considerably accelerates 
the rate of incendition by increasing the surface per unit of mass. 

Size of granulation. — In designing the granulation of the powder, 
the chemical composition of the colloid does not need to be consid- 
ered, as it does not alter for the various types of guns. The factors 
which affect the size of the grain are, first, the type of gun for which 
the powder is to be used; second, the weight of charge; third, the 




weight of the projectile ; fourth, the effect of the per cent solvent upon 
the shrinkage of the powder; fifth, the effect of the moisture and 
volatile content of the powder ; and lastly, the effects of the different 
methods of drying. 

Artillery is divided into three general classes: guns, howitzers, 
and mortars. Tschappat (Ordnance and Gunnery, J. Wiley & Sons, 
New York, 1917) describes the following types of artillery: 

Seacoast guns, field guns, mountain guns, anti-aircraft guns, and 
subcaliber tubes. 

The howitzers are classed as mountain howitzers and field howitzers. 

The mortars are seacoast mortars and trench mortars. 

In comparing the three types of cannon as to length, the gun is 
the longest, its length ranging from 40 to 60 times the bore of the 
gun; howitzers are medium in length, and mortars the shortest. 
Therefore, the mortar type would require a powder with a larger 
burning surface than either a gun or a howitzer of the same caliber. 
The gun, however, as a class gives the highest degree of accuracy, 
permits the longest travel of the projectile, and imparts the highest 
muzzle velocity. 

The calibers of seacoast guns range from 2.24 to 16 inches and are 
permanently mounted in fortifications. Field guns, or mobile artil- 



50 MILITARY EXPLOSIVES. 

lery, are designed to accompany or follow an army in the field, and 
are smaller in caliber, except in some of the railroad mounts. De- 
pending upon the type of the gun, however, the granulation of the 
powder must be so designed that the functions of the different guns 
are best served. 

Howitzers are used only in mobile artillery. "For each caliber of 
gun there is designed a corresponding howitzer of an equal degree of 
mobility, and the caliber of each howitzer is the same as that of the 
gun of the next lower degree of mobility. That is, the howitzer 
corresponding in mobility to one of the guns is of the same caliber 
as the next heavier gun and uses the same projectile." — (Tschappat, 
idem.) 

The seacoast mortars are short guns and in firing there is always 
a large amount of unburned powder slivers thrown from the muzzle, 
except when the sliverless or Walsh grain is used. This grain, as 
has been pointed out before, by providing a larger burning surface, 
burns quicker and thus eliminates this undesirable feature. Since 
each type of gun has its specified size of powder chamber, it is 
necessary to ascertain this capacity before designing the granulation 
of the powder. Other factors being equal, the greater the capacity of 
the powder chamber, the greater the size of the powder grains. If, 
for instance, the capacity of the powder chamber for the 12-inch mor- 
tar, model of 1890, is 2,674 cubic inches, and 12-inch mortar, model 
of 1912, 3,770 cubic inches, using the same weight of projectile (617 
pounds) and approximately the same weight of charge, the "average 
web" for model of 1890 is 0.0642 inch (Lot P. A. 199-1916) and for 
model of 1912, 0.0768 inch (Lot P. A. 198-1916). 

Effect of weight of charge. — When the weight of the charge is 
reduced there is a corresponding decrease in both the velocity and 
pressure developed on combustion. Within certain limits, however,, 
this lowered weight of charge can be effected, without sacrificing the 
pressure, by altering the granulation of the powder. The dimension 
most to be considered in this connection is the " average web." By 
this term is meant the mean distance which constitutes the least 
burning thickness from the edge of one surface to the edge of the 
next surface in the diametric direction. A full discussion of the 
dimensions of the powder grain will be found under section " green 
dimensions, die dimensions, dry dimensions, and web measurements." 
To decrease the weight of charge the average web must be decreased, 
but this decrease invariably causes increase in pressure with service- 
muzzle velocity; consequently there are limitations. From an eco- 
nomical standpoint the greatest efficiency is obtained when the de- 
sired muzzle velocity, with the maximum allowable pressure de- 
veloped just as the projectile starts moving, is produced by the least 
weight of charge. From a technical standpoint the greatest efficiency. 



MILITARY EXPLOSIVES. 51 

that is, the highest muzzle velocity with the same pressure, is obtained 
when the pressure increases as the projectile travels along the bore of 
the gun, until reaching a maximum at the muzzle; but in this case the 
powder efficiency is lowest. 

Effect of weight of projectile. — The following general classifica- 
tion of projectiles is indicative of the various types which have been, 
or are. in service (of these the high-explosive shell, shrapnel shell, 
and gas shell have been used most extensively) : 

Solid shot, cored shot, high-explosive shell, shrapnel, canister, and 
gas shell. 

An increased weight of projectile will result in an Increased maximum 
pressure in the gas if the same muzzle velocity is to be maintained with the 
same powder, size of powder chamber, and length of travel. — (Tschappat, p. 
518.) 

The maximum pressure for any gun being fired, the use of a heavier pro- 
jectile will usually require the use of a powder with a greater web thick- 
ness. Of two projectiles fired with the same initial velocity and elevation 
the heavier projectile will lose its velocity rnore slowly and will attain a 
greater range. For any given range it will be subjected for a less time to the 
action of gravity and other deviating causes, and will therefore have a flatter 
trajectory and greater accuracy. The advantages of the heavier projectiles 
are, therefore, increased range, greater accuracy, and a flatter trajectory. — 
(Tschappat, idem., p. 517.) 

Effect of solvent on shrinkage of powder. — It has been stated that 
a mixture of ether-alcohol is tised as a colloiding agent or solvent 
for the nitrocellulose. The excess solvent which is always present 
is eventually dried out during the solvent recovery and the dry house 
processes, and used again for the manufacture of ether. Depending- 
upon manufacturing conditions and the type of powder to be 
manufactured, the amount of solvent, in terms of dry weight of 
nitrocellulose, may vary from 80 to 105 per cent. For .30 caliber 
powder usually 105 per cent solvent is used; for reworked powders, 
90 per cent; and for cannon powders, 100 per cent. An excess of 
solvent enables the powder to pass through the press more easily, 
but on account of the softness of the grains they will dry unevenly 
and often blister and split. On the other hand, too little solvent 
not only delays the incorporation, but is likely to interfere with the 
perfect homogeneity of the powder. 

The per cent solvent used is nearly of as much importance from 
the ballistic standpoint as are the dimensions of the powder grains; 
in fact, this percentage influences, to a great extent, these measure- 
ments, for the greater the amount of solvent, the greater will be the 
shrinkage of the drying powder. 

Effect of moisture and, volatUes. — After graining, the bulk of the 
solvent is dried out, but 2 per cent to 8.5 per cent may remain in the 
powder as moisture and volatiles or total volatiles, the amount de- 
pending upon the size of the grain. No better description of the 



52 MILITARY EXPLOSIVES. 

effect of moisture and volatiles can be given than the following from 
Tschappat's " Ordnance and Gunnery " (idem.) 

The alcohol used in the solvent contains 5 per cent water, which generally 
remains in the powder after drying. Additional water may be absorbed from 
the air during the process of manufacturing and handling. Recent lots of 
powder also contain 0.4 to 0.8 per cent of a stabilizer, and .30 caliber rifle 
powders contain, in addition, 1 per cent of graphite. 

Smokeless powder may, therefore, be considered to be a mixture of nitro- 
cellulose, alcohol, water, and sometimes a stabilizer and graphite. Most of 
the ether used is evaporated out during the drying process. 

From calculations it is found that the energy per pound of pure nitrocellu- 
lose of 12.60 per cent nitrogen is 1,422,000 foot-pounds per pound. If not, an 
inert material, that is, one that takes no part in the reaction at combustion, is 
mixed with the nitrocellulose and the energy per pound of the resulting material 
will be less than that of pure nitrocellulose. For instance, if 0.99 pounds of 
pure nitrocellulose of 12.60 per cent N is mixed with 0.01 pound of inert 
material, the inert material will be 1 per cent of the total weight and the 
energy per pound of the resulting material will evidently be 1,442,000X0.99= 
1,427,580 foot-pounds per pound. 

Now, of the materials entering powder as given above, water is considered 
as having the same effect as the same percentage of inert matter. Alcohol has 
a greater effect than inert matter for the reason that the carbon contained in 
it combines with the C0 2 resulting from the combustion of the nitrocellulose, 
thus forming a larger quantity of CO and a smaller quantity of CO-, than in the 
combustion of pure nitrocellulose. Theoretical considerations and practical 
tests indicate that the effect of 1- per cent alcohol in reducing the energy per 
pound of nitrocellulose is equal to the effect of 2.5 per cent inert matter. 

In the same way the effect of 1 per cent stabilizer, which is higher in carbon 
content than alcohol, is shown to be equal to the effect of 4 per cent inert 
matter. Graphite, though entirely carbon, does not readily take part in the re- 
action and, therefore, the effect of 1 per cent graphite in reducing the energy per 
pound of nitrocellulose is considered equal to that of 2.5 per cent inert matter. 

Consequently, the granulation of the powder must be so calculated that it 
will counteract the reduction of the energy of the powder by the solvent re- 
maining after drying. In order to give more energy, the burning surface should 
be increased by diminishing the average web measurements or the size of the 
grain, or by changing the form of the grain. 

Effect of methods of drying. — The methods of drying which have 
been previously described in the process of manufacture affect both 
the ballistics and the stability of a powder. 

In the discussion of the alcohol dry system, mention was made of 
the fact that the strength of alcohol used influences, to a marked 
degree, the shrinkage of the powder. This shrinkage, however, can 
be regulated by varying the relative percentages of alcohol and water 
used in the process. While there is a tendency toward a greater 
shrinkage with alcohol-dried powder than with water-dried powder, 
the experiments at the present time seem to indicate that this factor 
will be easily controlled, since air-dried powders show the least 
amount of shrinkage. It is obvious that a larger allowance in 
measurements should be made for the powder which has the greatest 
shrinkage and, therefore, the die dimensions of the air-dried pow- 



MILITARY EXPLOSIVES. 



52a 




Plate 31. — Die Body, Pin Plate, Plug, Water Jacket, Water-Jacket 
Head, and Smokeless Powder Grain for 12-Inch Gun. 

132569—19 6 



MILITAKY EXPLOSIVES. 



53 



ders should be correspondingly smaller than those for the " water- 
dry : ' or " alcohol-dry " powders. 

In considering the length of the powder grain in reference to its 
diameter it is known that if the green length is more than 1.875 times 
the green diameter, the grain will warp excessively and dry unevenly. 
On this account and in order that the grain may serve for convenient 
building into charges, as well as other factors, its length is limited. 
The requirement of prompt ignition throughout the length of the 
grain also limits this dimension, and by allowing 8 per cent shrinkage 
in length, and 30 per cent shrinkage in diameter, this will make the 
length of the dry grain a little less than two and one-half times the 
diameter. The per cent increase allowed should increase two-thirds 
per cent for every per cent increase in solvent. 

Before designing the dimensions of the multiperforated, single per- 
forated and sliverless grains, it will be necessary to understand the 

\AMTER JACKET- C, WATER INLET Z5PPZ TAP 

•maimi'i/iti'in 




7777]/lll>!/l!>.>tr>ll!l!!>>!>/!. 



^k?& 




DIE BODY-/W PIN5-E- / ka-OSNG SCREW- D 

WHTER OUTLET ZSPPt TAP 

POWDER DIE ASSEMBLY 

U5ED TOR CYLINDRICAL CiRAIN?) 

Plate 30. 

following terms : Green dimensions, die dimensions, dry dimensions, 
and web measurements. 

As the powder comes from the graining press it contains from 40 
per cent to 50 per cent solvent and is called " green " because the 
solvent has not been extracted by the drying processes. The " green " 
powder has about the same dimensions as the steel die and pinplate 
through which it has just been pressed. The die body A consists 
of a steel block designed to hold the pinplate B, the water jacket C 
(having an inlet and outlet for water used for cooling the die while 
running the powder) and a closing screw D for the water jacket. 
The pinplate consists of a perforated plate, to which are attached 
the wires or pins E, which form the perforations in the grain, and 
the plug F, which holds the pins in place. The dimensions for both 
the die body and pinplate are called die dimensions. 

It is necessary to calculate the dimensions of the die very ac- 
curately, as there are many factors which cause the measurements 
of the green powder to differ from those of the die. Among these 
factors is the spring of the pins (or needle wire) by which action 
the pins are drawn together as the powder is being pressed through 
the die, and which has the effect of decreasing the "inner web." 



54 MILITARY EXPLOSIVES. 

Another factor is the consistency of the powder as it is being 
grained. The softer the powder, the more it will contract as it 
goes through the die, thus causing the green dimensions to be less 
than the die dimensions. 

Dry dimensions. — Before the powder can be used, the solvent 
must be dried out so as not to leave over 8.5 per cent for the largest 
granulations and not over 2.5 per cent for the smallest granulations. 
The percentage of solvent is first reduced by the solvent recovery 




Plate 32.— Wa= 



Wi+Wo 



2 

process and finally by placing the powder in dry houses for a period 
of from 15 days for .30 caliber powder to three months or more for 
16-inch powder. The powder is then blended and samples are taken 
for measurements and other tests. The measurements taken from 
the dry finished are called dry dimensions. 

Web. — By the web of a powder grain is meant the minimum 
burning thickness, or the distance from the edge of one surface to 
the next surface in the diametric direction. There are three of 
these measurements: "Outer web," "inner web," and "average 
web." The outer web is the distance from the circumference of the 
grain to the nearest edge of the outer perforation. The inner web, 



MILITARY EXPLOSIVES. 



55 



found only in multiperfo- 
rated grains, is the dis- 
tance between the inner 
edge of the perforation 
midway between the cen- 
ter and the circumference, 
and the nearest edge of 
the central perforation. 
The average web is found 
by adding two inner webs, 
two outer webs, and divid- 
ing by four. The symbol 
used for outer web is W , 
for inner web W t , and for 
average web W a . The 
average web is given as a 
basis for all other compu- 
tations, and the purpose 
of the following calcula- 
tions is to indicate the 
procedure used in com- 
puting the measurements 
for a die, from a standard 
average web measurement. 

To calculate an entirely 
new average web for the 
powder of a new gun re- 
quires a knowledge of in- 
terior ballistics and ex- 
plosive theories, which is 
not within the scope of 
this book. An excellent 
and detailed explanation 
for calculating a new 
powder is given in Tschap- 
pat's Ordnance and Gun- 
nery, Chapter IV. 

The calculation on the 
average web, which will 
be discussed, involves 
merely the change of the 
die measurements which 
may be made in order to 




CyLiNDHic/tL Grains 7 PeRroRAT/GHS. 
Dry Dimensions (Approx) 
D = 10 d 
M/o=5 7o +V/t 

D = outside diameier 

d = diameter of perforation 

Wo= outer web 

Wi = inner web 




Cylindrical Grain Single Perforation 
Dry Dimension, D-3d 

D- outside diameter. 

d = diameter of perforation 



Plate 33. 

conform to the different processes of manufacture, and to create 
better ballistic results for a new lot of powder. 



56 MILITARY EXPLOSIVES. 

Perforation. — The perforation or pinhole of a powder grain is the 
hole in both single and multiperforated powders made by the needle 
wire of the pin plate. The diameter is always the required measure- 
ment of the perforation and is expressed by the symbol " d." 

Diameter. — The capital D signifies the outside diameter of the 
grain, passing through its center and terminating in its circumfer- 
ence. In the multiperforated grain it includes three perforations and 
is calculated mathematically as the sum of two outer webs, two inner 
webs, and three times the diameter of the perforation or 
D^Wo+SWi+Sd. 

Needle wire. — Needle wire consists of steel rods, set in the pin 
plate as shown in the diagram, and which form the perforations in 
the powder as it issues from the die head. There are standard sizes 
of needle wire usually kept in stock at the factories, and the calcula- 
tions of the die can be made to conform to the standard needle wire. 

Pin circle. — The pin circle is formed by drawing a circle through 
the center of the six outer perforations. The diameter of the pin 
circle is calculated as the sum of the two inner webs and the two 
diameters of the perforation. This equals 2Wi+2d. The pin plates 
are classified according to the diameters of the pin circles. 

Slope of cone. — The powder is pressed through the die at a given 
angle and it depends on the consistency of the colloid whether the 
powder should be fed to the press slowly or quickly; for cannon pow- 
der the anjde at which the colloid enters the die should be about 45 c 
and for small arms about 30°. 

Quirk powder — Slow powder. — Wise (Gunnery, J. C. Wise, John- 
son Publishing Co., Richmond, Va., 1912) gives the following defini- 
tions of quick and slow powders : " A powder with greater initial 
surface than the standard powder — that is, a powder of smaller 
granulation, will produce a greater maximum pressure and there- 
fore will be a quick powder for the gun, and a powder of larger 
granulation will be a slow powder." Another factor to be consid- 
ered in this connection is the percentage of " total volatiles." The 
higher this per cent the slower the powder, and the lower the pres- 
sure for a given density of loading; and conversely, the lower the 
per cent, the quicker the powder, and the higher the pressure for a 
given density of loading. 

Calculation of average dry web. — The basis for all calculations of 
powder dimensions is the average web of the dry powder. As has 
been pointed out, the factors affecting this dimension include the per- 
centage of solvent and the method of drying the powder. There are 
relatively wide variations in practice by the different manufacturing 
companies — variations which are necessitated by the differences in 
manufacturing technique, as well as by climatic conditons. Al- 
though the maximum temperatures of air drying and water drying 



MILITARY EXPLOSIVES. 57 

are specified, the contractor is given enough leeway to insure a maxi- 
mum speed of drying without injury to the grain. In other words, 
as long as the finished powder meets the required specifications, the 
minute details involved in the manufacturing process are of little con- 
sequence. Each company issues a description sheet which indicates 
both the die and dry measurements. For determining the best aver- 
age dry web, it is neeesasry to take the dimensions of the powders 
which have been given the best ballistic results. This information 
is obtained from an examination of the firing records, charge, velocity, 
and pressure curves, and if these are not available, the average dry 
web of any accepted powder can be taken as a basis. It is the aver- 
age web of the die that is difficult to calculate because that measure- 
ment takes into consideration all the processes of manufacture, such 
as per cent solvent used, method of drying, moisture, and volatiles, 
etc. 

Calculation of required dry dimensions. — When the average web 
has been determined and complies with the standard dimensions, the 
next step is to determine, theoretically, the other dimensions of the 
dry powder — that is, the outer web, the inner web, the diameter of 
perforation, the outside diameter and the length. The outer web is cal- 
culated as 5 pei- cent larger than the inner web. This is found by 
dividing the average web by 0.975 to obtain the outer web, and by 
dividing the average web by 1.025 to obtain the inner web measure- 
ments. 

The diameter of the small perforation (d) is determined from the 
following formula : 

d=4Wa 



Theoretically, the outside diameter (D) equals ten times the diam- 
eter of the small diameter, or D=10d. In order to check this, another 
formula is used : 

D = 2W +2Wi+3d. 

The length of the dry grain is calculated as two and three-eighths 
to two and one-half times the outside diameter (D). 

The dry dimensions for a single-perforated grain are calculated 
differently. As there is only one web measurement, the outer web 
is the same as the average web and also the same as the diameter of 
the perforation (d). This would make the outside diameter (D) 
equal three times the average web, or 

D=3d. 

The dry length of the single-perforated grain is equal to three 
times the outside diameter, or 

L=3D. 



58 MILITAKY EXPLOSIVES. 

Calculation of per cent shrinkage. — When all the above required 
dry measurements have been calculated and before the dimensions 
of the die can be determined, it is necessary to find the per cent of 
shrinkage for the average web measurement. This is very difficult 
to determine accurately because so many factors influence the amount 
of shrinkage. It has been stated that the greater the amount of sol- 
vent used the greater the shrinkage. An increase of two-thirds per 
cent shrinkage is allowed for every per cent increase in solvent. Air- 
dried powders have a smaller per cent of shrinkage than either water 
or alcohol dried powders. The per cent shrinkage of the multiper- 
forated grain varies from 25 to 35 per cent. This shrinkage can also 
be determined by reference to the shrinkage of powder of other 
manufacturers, as noted on the description sheets, but care must be 
taken to consider the processes employed (such as solvent, drying, 
etc.), which affect equally the shrinkage. 

Calculation of die dimensions. — When the per cent shrinkage for 
the average web has been determined, the next step is to calculate 
the average web of the die. It is found by the formula — 

. .. required dimensions of dry grain 

Average web of die= : 

1 — % shrinkage allowed. 

The result of this calculation gives the basis for the calculation of 
the other dimensions of the die such as W , W i? d, D, and L. The 
same procedure is employed as described under the dimensions of the 
dry grain. These results are only preliminary and are not, in any 
sense, arbitrary measurements, for the inner and outer web measure- 
ments are always changed. The inner web of the die is often de- 
signed to be larger than the outer web, which is contrary to that 
required in the dry powders, for the reason that the spring of the 
pins as the powder presses through the die decreases the inner web 
thickness. Since the inner web thickness of the die, as shown in the 
records, shrinks more than the outer web, the inner web should be 
the larger of the two. But in some cases, however, the die dimen- 
sions of the inner and outer webs are the same, due to the varying 
factors in the manufacturing processes. In fact, there is no specified 
rule for finding the percentage of difference between the two measure- 
ments of the die. It must be found either by reference to other dies 
made for the same powder, or through experience in manufacture. 
Other dimensions of the die may also be changed to meet existing 
conditions. If, for instance, there is needle wire in stock which is 
0.001 inch at variance to the designed die, the calculation for the 
diameter of the perforation (d) may be altered to conform to the 
needle wire on hand. It is, therefore, impossible to arrange any ar- 



MILITARY EXPLOSIVES. 59 

bitrary rules for die calculations because of the various differences 
in drying processes and shrinkages. 

Thus far there have been calculated the die dimensions for a ten- 
tative granulation. The next step is to find the per cent of shrinkage 
between the die and the dry dimensions. This shrinkage is found 
by using the formula — 

„ , . , ,, , . (required dimension of dry grain) 

% shrinkage allowed =1 — - — j^. -■ * v \ 

' & (dimension of die). 

If this shrinkage does not seem to be within reason or within the 
prescribed limits, it must be changed to conform with the actual 
shrinkage of similar powders. Changing the shrinkage changes the 
die measurements and these figures must be changed again to 
conform to the formulae and specifications until a satisfactory die 
with satisfactory calculated shrinkage is obtained. It is best not to 
change the required dry dimensions unless absolutely necessary, and 
in any case the average web of the dry dimensions must not be 
changed. 

Measurement of green powder. — After the dimensions of the die 
have been calculated, the drawings made, and the die bodies and pin- 
plates manufactured in the machine shop, the next measurements are 
those of the green powder at the time it is being grained. This is 
very difficult of accomplishment, as the powder has to be cut and 
measured quickly and accurately. The method consists of cutting 
approximately one-fourth the length of each of three powder grains. 
The first grain is taken and measured when one-tenth of the block 
of powder has been pressed through the die; the second grain is 
taken when one-half the block of powder has been grained, and the 
third grain when nine-tenths of the powder block has been grained. 
A microscope having a micrometer stage attachment is used for ob- 
taining the measurements by the same method as previously described 
for measuring dry powder, and the results should show that the 
powder has an outside web thickness greater than the inside web 
thickness. The outer web may exceed the inner web by 15 per cent, 
but the inner web may not exceed the outer web by 5 per cent. These 
percentages are calculated on the average web thickness. If these 
trial measurements do not fulfill the requirements, the dimensions 
for a new pinplate must be calculated. If the outer web is too heavy 
it may be made smaller by increasing the diameter of the pin circle. 
This has the effect actually of increasing the inner web ; on the other 
hand, in the event that the inner web is too heavy, it is necessary 
to design a new pinplate with a smaller pin circle. With these 
changes, the calculated shrinkage must be redetermined in accordance 



60 MILITARY EXPLOSIVES. 

with the formula given above. The alteration of the die should not 
include a change of the outside diameter of the die (D), for the 
reason that such a change would necessitate the use of a new die 
body. The three dimensions which may be altered as necessity 
dictates are, the inner web, outer web. and diameter of the perfora- 
tion. 

Failure of powder in ballistic tests. — In the event that the ballistic 
test shows the lot of powder is too quick or too slow T , thus resulting 
in the failure of the powder ballistically, these circumstances necessi- 
tate the recalculation of the die dimensions for the graining of 
another lot of powder. If the powder is too slow, the average web 
must be decreased, provided that the outside diameter is not changed. 
If the powder is too quick, the web average must be increased with- 
out altering the diameter. If the powder passes all the ballistic and 
physical tests, it proves that the design of the die is satisfactory and 
may be considered as a standard. 

Formula' for burning surfaces. — The calculations of the burning 
Mtrface of a powder grain are necessary to determine the " quickness " 
or " slowness" of a powder. The pressure of the gases from the 
burning powder varies directly as its burning surface. The burning 
surface was formerly considered the standard dimension by which a 
satisfactory poAvder was recognized, but dining the last two or three 
years all powders are gauged by their average web thickness. 

The following series of formula? show how the algebraic expression 
for the burning surface was derived. It is the product of the number 
of grains per pound multiplied by the surface of one grain : 

A =area of one end of grain. 

A' =area of seven holes. 

d == diameter of perforation in inches. 

D = outside diameter of grain in inches. 

L = length of grain in inches. 

N = number of grains per pound. 

s = surface of one grain. 

S =burning surface of one grain. 

V = volume of one grain. 

W =web thickness or average web. 

W t =web, inner. 

W =web. outer. 

D 

x =d 
L 

7 =T> 

7c =3.1416Xi=.7854 

c = specific gravity of powder. 



MILITARY EXPLOSIVES. 61 

Formulae for burning surface — Cylindrical grain — Seven perforations. 

1. The formula for the surface of one grain is as follows: 

5[(D 2 x.7854)-(d 2 X.7854x7)] + 7rdL7 + 7rDL 
= (2D 2 X .7854 - 2d 2 X .7854 X 7) + 7rdL7 + ttDL 

= ^2D 2 x^-2d 2 x|x7) + [7rL(D + 7d)] 

^=|D 2 -|7d 2 +|[2L(D + 7d)] 

= ^[D 2 -7d 2 +(2L(D + 7d)] 
= surface. 

2. The volume of one grain is equal to the area of the base times 
the length : 

(D 2 X .7854 - d 2 X .7854 X 7)L 



(D 2 x;-7d 2 x^)L 



= |(D 2 -7d 2 )L 
= volume. 

3. There are two methods for calculating the number of grains 
per pound: One by physical measurement described on page 110 
and which is performed in the laboratory; the other by calculating 
from the following formula : 

LO 

[(D 2 X .7854) - (d 2 X .7854 X 7)].036 1L5 
1.0 

|(D 2 -7d 2 ).036lL5 

1.0 

(D 2 - 7d 2 ) .02835294L5 
= number of grains per pound. 

4. The following series show how the formula for burning sur- 
face has been found. It is the product of the number of grains per 
pound and the surface of one grain. It is measured in square inche? 
per pound: 

((D 2 -7d 2 ) 1 0283W4L5) (^-7d 2 + (2L(D + 7d))]) 
^[D 2 -7d 2 + [2L(D + 7d)]] 

= ~ (D 2 - 7d~ 2 )iJ2835294TJ 
D 2 -7d 2 + [2L(D + 7d)] 



(D 2 -7d 2 ).01805L5 
= burning surface square inches per pound. 



62 MILITARY EXPLOSIVES. 

5. In the following formula N is determined by weighing any con- 
venient quantity, counting the grains and calculating from this data 
the number of grains per pound as follows : 

|N[D 2 -7d 2 + (2L(D + 7d))] 

|=1.5708 

= burning surface square inches per pound. 

Formulae for burning surface — Cylindrical grain — Single perforation. 

6. The following formula gives the surface of one grain : 

2 (D 2 X .7854 - d 2 X .7854) + irdL + ttDL 
= (2D 2 X^-2d 2 x|V[7rL(D + d)] 

= D 2 x|-d 2 X^ + |[2L(D + d)] 

= |[D 2 -d 2 + 2L(D + d)] 

-|(D-d + 2L) (D + d) 
= surface. 

7. The volume of one grain is equal to the area of the base times 
the length : 

(D 2 X.7854-d 2 X.7854)L 

= (D 2 xf-d 2 xj)L 

= £(D 2 -d 2 )L 
= volume. 

8. The number of grains per pound can be calculated by actual 
measurement as described on page 110 and it can also be found by 
the following formula : 

1.0 

. £(D 2 -d 2 ).036lL5 
1.0 



(D 2 -d 2 ).02835294L5 
= number of grains per pound. 



MILITARY EXPLOSIVES. 



63 



9. From the above formulae, the formula for burning surface is 
found by multiplying the number of grains per pound by the surface 
of one grain : 



TV 



(D-d+2L) (D + d) 

(D 2 -d 2 ).02835294L5 

_[( D-d) + ( 2L)](D + d) 
(D 2 -d 2 ).01805L5 

= burning surface square inches per pound. 

10. In the following formula N is determined by weighing an 
approximate quantity and counting the grains, calculating from this 
data the number of grains per pound : 

TV 

^N(D+d) (D — d + 2L) = burning surface square inches per pound. 
Formulae for burning surface — Sliverless grain — Seven perforations. 

11. There are several methods for calculating the burning surface 
of the sliverless grain, using different geometrical forms, and the 
following formula has been calculated from the accompanying geo- 
metrical figure, which is a simple problem in geometry : 



S = 



2A + 6lL + 77rdL 
ALx. 0361X5 




12. Another formula for the burning surface of sliverless grains is 
given in the Inspector's Manual as : 

S = JN[2tt(D(4L + D) + 14d(2L - d)) + 3D 2 V 3 ] 

where N— number of grains per pound. 



CONCLUSION. 



General considerations. — It has been found that, on the whole, the 
cylindrical form of grain is most satisfactory ; that 100 per cent sol- 
vent is the average amount used for regular cannon powder; that 
air-dried powders give a smaller per cent shrinkage and their dies 
are therefore easier to calculate. 



64 



MILITAKY EXPLOSIVES. 



In calculating the dies for powder, the average web is taken as a 
basis and the dimensions are first calculated by formula and then 
changed as conditions in manufacture require. If a powder is too 
quick the average web must be increased, and if too slow, decreased. 

Eecords should be made of all powders calculated on cards similar 
to the following data card : 



NMOKKLKSS POWDKK DATA. 



Size 



Model 



Lot No 



WO 



DIE NO. 



]']N l'l.ATK NO. 



I)W(1. NO. 



REV. 



FORM OF (JRA1N 



I) 



Wo 



W 



Wh 



nil. Pin 

Circle 



Kind or 
Plus 



Slope of 
Cone 



Dimensions of Hie 



fe Shrinkage Allowed 



Required Dimensions 
of Dry Grain 



Grained 
From 
To 



Measured Dimensions 
of Dry Grain 



L:D(y) 



Req: Actual 



Wt. of Lot Packed 



I 



D 

Req 



:d (x) 

Actual 



Actual Shrinkage * 



V Solvent 



Elher 
Alcohol 



No. of Perioral Ions 



Gravimetric Density 
Lbs. perCu. Ft 



Kef. P. A. 



Toul Vol. (D. H.) $ 



Total Vol. (Pkd.) % 



Alcohol 
Wain 



No. Grains Per Lb 
(Finished) 



Burning Surface Per Lb. 
Sq. Ins. (Finished) 



Required 



Required 



Sp. Gr. 



Dlff. Between Wl and Wo 
Ip % of Wa (Finished! 



RequirKl 





CUTTER NO 






CUTTER NO. (NAVY) 




0,1 c,r nniviw 


No Teeth Drl 


eR 


DRIVING 
CEARS - 


No. Teeth DrlveR 


FEED 
ROLL 




No. Teeth Drii 


eN 


No. Teeth DrlveN 




Dwg. No. 


D. Pitch 


D. Pitch 




Dla. Clr .,__, 


No. Holes 


Worm 


BAND 
WHEEL 


Face PTATF 


Dia of Holes 


No. Teeth Worm Gear 




Dwg. No. 


iHVg. No. 


No. Knives 




No. Teeth 


Ill' 


FwJ Rolh Dil Bot Groove Angle 




Bet. Cutting Edges MOTOR 


R l>. M 




HP 




Length of Tool h 


Dia Pullet 


MOTOR 


R. P. H 


BAND 


Width ul Slot I'lllll'J on 


Culler 


hii. 




Dia. Pulley 




Thickness II. I». M Rami Wheel 


Pulley on Cutler Dla. 




Width II. I 1 M. Full It.. II 


It P. M. Knife 




Length Trawl ..I llund 


Kl. Pel Mill. 1 






No. Teeth Ci.ie.1an1 




FEED 
ROLL 
GEARS 


Pitch Din 
D. I'll.li 











FINISH INC I'WKNN 

NO. M|B „., A „ F,,, l .-M 1 „o., ""••- HI.I.I.KIIS 



Plate 34. 



CHAPTER III. 

STABILITY OF SMOKELESS POWDER. 

The subject of stability of smokeless powder involves both safety 
in storage and uniformity in ballistics. In the discussion upon the 
purification of nitrocellulose, it was pointed out that the processes 
of boiling are made necessary from the fact that a pure product, or 
more properly, one definite nitrate, can not be prepared. The present 
knowledge of the cellulose molecule and of the intermediate reac- 
tions occurring during the nitration of the molecule, limits any at- 
tempt at the preparation of a single nitrate, and while the complete 
hydrolysis of the lower nitrates is sought in the boiling processes, 
there is no assurance that this reaction is the only one concerned, nor 
is it proven that there are not other factors influencing the speed and 
the completeness of the reaction. In spite of the elaborate process 
of purification followed out to insure the stability of the finished 
powder, this program is extended by incorporating in the colloid 
four-tenths per cent dry weight of diphenylamine. 

STABILITY TESTS. 

The powder is said to be stable or is said to have good stability 
when it passes the KI test, the 135° test, and the test in the two sets 
of surveillance chambers, one of which is maintained at a tempera- 
ture of 65.5° C. and the other at 80° C. 

There is no test, however, of the stability of smokeless powder 
which is infallible, or which indicates in more than a general way 
the safety of the powder from the storage standpoint. The idiosyn- 
crasies and the unreliability of the KI test are too well known to 
require more than passing mention. The 135° test serves as a cri- 
terion for the incomplete hydrolysis of the lower nitrates and for 
the presence of sulphuric esters (cellulose sylphates). Any of these 
are capable of giving a low test for "salmon pink." There is a good 
deal of discussion, however, upon the points involved, and research 
work projected along physico-chemical lines would throw much 
needed light upon this subject. 

The surveillance tests of smokeless powder are unsatisfactory from 
the standpoint of uniformity of results and also from the standpoint 
of elapsed time necessary to obtain any data. 

65 



66 MILITARY EXPLOSIVES. 

CAUSES OF INSTABILITY. 

Worden points out (Nitrocellulose Industry, Worden, D. Van 
Nostrands Co., New York, 1911) that the stability of cellulose ni- 
trate may be influenced by any or all of the following factors : 

First. The formation during the process of nitration of sulphuric 
esters, which are not entirely eliminated in the subsequent purifica- 
tion processes. 

Second. The presence of hydro- and oxy-cellulose in the cellulose 
before it is nitrated. This point has already been emphasized in the 
discussion on nitration, where it was pointed out that the over- 
bleaching of the raw material yielded a product relatively high in 
soluble cellulose. 

Third. Traces of free acid. 

Fourth. Traces of organic impurities, such as waxes and resins. 

Fifth. The presence of fungi or other microorganisms. 

Sixth. The presence of such vaguely characterized bodies as nitro- 
saccharoses or pectins. 

STABILIZERS. 

Prior to 1908 little was done from the manufacturing standpoint 
to standardize the methods of purification then in practice. In fact, 
the importance of the whole subject of stability of explosives was 
not recognized to the same extent as at present and consequently had 
not received the same consideration. In the mixing of the colloid, it 
was the practice to incorporate a small amount of an organic dye 
which served the purpose of an indicator rather than a stabilizer. 

The indicator which found the widest application was rosaniline, 
and its adoption was due to the fact that upon the development of 
any marked acidity produced from the decomposition of the smoke- 
less powder, the red color of the dye in the powder grains faded to 
a yellow, which fact serves to indicate the instability of the powder. 

The use of diphenylamine was not general until the latter part of 
1908, and its function was different from that of Kosaniline, for it 
has the property of combining with free N0 2 . Upon the develop- 
ment of those free oxides of nitrogen in smokeless powder, the di- 
phenylamine undergoes progressive nitration (Buisson, " Problems, 
Des Poudres," P. Juillard, Bui. Soc. Chem. 33, 1905, p. 1172), as 
indicated in the following series of reactions: 

(C 6 H 5 ) 2 NH (C 6 H 5 ) 2 N.NO C 6 H 4 (N0 2 ).N(NO).C 6 H 5 

diphenylamine diphenyl-nitrosamine nitro-diphenyl-nitrosamine 
(C 6 H 4 N0 2 ) 2 NH C 6 H 4 (N0 2 ) .N.C 6 H, (N0 2 ) 2 

dinitro-diphenylamine trinitro-diphenylamine 



Ml I.I I \U\ KXl'LOSIV ES. 



fiC>rt 




MILL FOR REWOKING 

UNSTABLE POWDER. 

SMOKELESS POWDER FACTORY 

PICATINNV ARSENAL. 



Plate 35. 



132569—19 7 



MILITARY EXPLOSIVES. 67 

These separate substances may be detected by various quantitative 
and qualitative reactions, and when an}' of the tests applied to the 
powder are positive, they indicate an impaired stability. 

REWORKED POWDER. 

The reworking of smokeless powder, which is in effect a salvaging 
of unstable powder, is a relatively new development in the manufac- 
ture of this propellant and is, therefore, experimental from many 
standpoints. The subject of stability of organic nitrates, of which 
this material is an example, and of organic nitro bodies is one of 
very prime importance, particularly when large amounts of explosive 
are being stored. In fact, the whole storage problem is so intimately 
related to stability that a consideration of the one necessarily involves 
the other. 

When storage tests and surveillance results give warning of an ap- 
proaching impaired stability of a quantity of smokeless powder, the 
particular lot so affected is withdrawn from general magazine stor- 
age, each powder container opened and the contents flooded with 
water. In the event that the lot in question is a nitroglycerin powder 
or a coated powder such as a graphited powder, the lot is destroj'ed 
at the burning ground. This procedure is made necessary for the 
reason that it is impracticable from the standpoints of both economy 
and safety to rework such powders. If, hcwever, the powder show- 
ing imj)aired stability is a so-called " straight nitrocellulose " powder, 
the reworking can be accomplished economically and efficient^. It 
is necessary, however, to determine the nitrogen content in the un- 
stable powder, for a powder whose instability has progressed to such 
a degree that the loss of nitrogen brings the percentage of the total 
nitrogen below 12.10 per cent can not be reworked to advantage. A 
powder failing to show at least this percentage is burned as in the 
case of the nitroglycerin and coated powders. 

The fabrication of reworked powder differs from that of straight 
powder in that there are no nitrating, boiling tub, or pulping proc- 
esses involved. Instead of this the powder grains are pulverized 
under water by a heavy steel wheel mill weighing 5 tons, until the 
particles of powder are so finely comminuted that they float on the 
surface of the water. A discharge pipe from the mill conveys the 
material to a screen having a mesh of twenty-six hundredths of an 
inch, where the coarser particles of powder are separated out and 
returned to the mill for further grinding. The grinding operation 
is therefore of a continuous nature and more old powder is added 
from time to time, depending upon the hardness of the grains being 
worked and the speed of the mill. 



68 MILITARY EXPLOSIVES. 

After this preliminary screening the material is repurified in a 
manner similar to that employed in the poaching treatment of the 
regular pyro. The reworked pyro at this stage is very dissimilar 
to the regular pyro and presents many obstacles from the manufac- 
turing standpoint. It is 3 T ellowish in color, does not respond readily 
to the purification treatment, is difficult of manipulation in the 
wringers on account of the dense cake it forms on the screen, and 
offers many problems in chemical analysis, especially when deter- 
mining the percentage of nitrogen. In the dehydrating presses the 
utmost care must be exercised, for on different occasions the careless 
manipulation of the pressure valves has resulted in the blowing up 
of the press, with its attendant fire and loss of life. The dehydrated 
block, unlike the regular pyro, is more friable and is in fact so lack- 
ing in cohesiveness that it can not be put in the block-breaker prior 
to the mixing operation. 

Its photomicrograph also shows certain definite differences, one of 
the most striking being the reduction in the number and size of the 
fibers, thus indicating the action of the previous colloiding operation. 
It is largely due to this fact that reworked pyro granulated for 6- 
inch gun, model 1900, 1903, and 1905, and 75-mm. gun, model 1897, 
requires only 90 per cent solvent as against 100 per cent in regular 
pyro. 

After the colloid has been formed, however, the treatment in both 
the factory and dry house does not differ materially from that given 
the regular colloid. 

STORAGE OF SMOKELESS POWDER. 

It has already been pointed out that the moisture and volatile con- 
tent of smokeless powder is an important factor in determining the 
weight of charge and the pressure to be expected for the required 
muzzle velocity. In order that this percentage will remain constant 
it is necessary that the powder be stored in air-tight containers so 
constructed that they may be easily filled, tested, piled, and emptied. 
With small arms powder it is customary to line the inside of the 
container with a muslin bag, the object being to keep the powder en- 
tirely free from dust, chips, or other extraneous material. 

The powder container consists of a wooden box, zinc lined, about 
26 by 16 by 11 inches. There are two types, the so-called export type, 
having a capacity of 140 pounds of smokeless powder, and the other, 
the Picatinny Arsenal type, having a capacity of 110 pounds of 
smokeless powder. The cover is provided with an outside ring, 
locking ring, and rubber gasket, assembled in such a way that when a 
lever is forced down on the top of the box, tension is put upon the 
lugs in such a manner that there is no possibility of air leaks. Each 



MILITARY EXPLOSIVES. 69 

box is tested before being filled by having a small hole drilled in the 
cover, applying compressed air, and noting the reading on the pres- 
sure gauge attached to the air line. 

The magazines for the storage of smokeless powder should be kept 
dry, and should be so situated that there is a minimum variation in 
temperature. This latter point is an important one from the stand- 
point of maintaining the standard moisture and volatile content. In 
those instances where a wide range in temperature obtains there is 
always the added risk of the powder containers tending to develop 
leaks, due to the difference in the atmospheric pressure inside and 
outside of the zinc boxes. The most satisfactory storage conditions 
are those which insure a free circulation of cool, dry air. The venti- 
lation, therefore, of the magazine is a very important point and 
should be so controlled that air will not be admitted when condi- 
tions on the inside of the magazine are such that condensation of 
moisture within the magazine would follow. The containers should 
be handled the least possible number times, and whenever such han- 
dling is necessary it should be done with the greatest of care, the ob- 
ject being to obviate any possibility of air leaks being produced in 
the containers. 

In piling, the boxes are placed on their broad side. They should 
not be piled closely together for the reason that such a procedure 
defeats a proper ventilation. When properly placed, however, they 
may be piled 12 high, provided the magazine space permits. The 
important preliminary detail of cleanliness of the magazine floor 
should not be overlooked, for the accumulation of dirt, rubbish, and 
nails, aside from being unsightly, constitutes a menace. Scrapers 
should be placed at the door of the magazine so that mud, cinders, 
gravel, or other material will be removed from the shoes before the 
powder is stored. Under ordinary conditions it is not necessary to 
w T ear powder shoes in the magazine, except in the case of repacking, 
when it is advisable that this precaution be observed. 

The magazines must be so located that good drainage of the land 
is possible at all times. This is of special importance where large 
quantities of smokeless powder are being stored. In spite of the 
precaution observed for the elimination of leaky powder cans, the 
fact remains that there are many instances where the leaks are not 
discovered. This results, of course, in the powder in such cans ab- 
sorbing moisture from the damp atmosphere in which it is stored, 
a condition very undesirable from the ballistic standpoint. The 
fire risk is not of serious consideration if the necessary precautions 
are observed. The danger of grass fire is practically nil if brush and 
undergrowth are removed for a distance of 50 feet around the build- 
ing. The carrying of matches or flash-producing devices of any kind 



70 MILITARY EXPLOSIVES. 

should be strictly prohibited. This rule may be enforced by having 
those employees associated with the storage depot searched for 
matches in their clothes at irregular intervals. Smoking, of course, 
should be absolutely forbidden at all times where explosives are 
manufactured, tested or stored. Oil-burning lamps, lanterns, candles, 
etc., should be prohibited, and in those cases where artificial light is 
required special storage-battery lamps should only be used, or for 
short inspection the ordinary dry battery flashlight. 

When it is necessary to renail boxes, nonsparking tools should be 
used. These consist of copper hammers, wooden mallets, copper 
nails, etc. The use of metal hooks for the moving of packages of 
high explosives or ammunition should not be permitted. When cir- 
cumstances are such that it is impossible to get explosives under 
cover, a tarpaulin should be thrown over the exposed material, but 
in the event that an explosive becomes damp from inclement weather, 
it should be piled separately from the other explosives and a special 
chemical examination be made of the wet material. 

Each magazine should be provided with a minimum and maximum 
thermometer, and careful record should be kept at all times of the 
variation in temperature. Except when material is being checked in 
or out of the magazine, or during inventory, the building should be 
kept securely locked. Under no circumstances should packages of 
explosives or ammunition be opened within the magazine. If it is 
necessary to examine material, it should be done outside of the build- 
ing and far enough away so that in the event of accident the build- 
ing itself would not be endangered. 

Damaged packages should in every case be removed from the 
magazine and taken to a special repacking house before any attempt 
to salvage the material is made. If the damage is slight and a 
repacking house is not available, any repair or recoopering may be 
done outside at a distance not less than 100 feet from any magazine. 

The transportation of explosives should be governed primarily by 
the rules of the Interstate Commerce Commission. These provide 
for the safety in transit of certain so-called acceptable explosives, 
provided that they comply in every way with the rules for packing 
and marking. Where shipment is in carload lots, each tier of boxes 
or containers must be carefully cleated and braced to provide against 
any possible misplacement through jar or shaking of the car. 



CHAPTER IV. 
INSPECTION OF SMOKELESS POWDER. 

The foregoing consideration of the manufacture of smokeless 
powder emphasizes the prime importance of careful chemical super- 
vision throughout the factory and demonstrates that standard meth- 
ods of analysis are necessary if comparative results from different 
factories are to be of value. The purchase of the raw materials, 
such as cotton, acids, alcohol, and diphenylamine, is governed by 
specifications so designed that a uniform quality of material will 
be obtained. As these specifications are, necessarily, of a chemical 
nature, it becomes the function of the laboratories to exercise care- 
ful supervision and control over all raw materials purchased. 

With this in mind, there has been. compiled a set of detailed in- 
structions, based upon methods which have been successfully fol- 
lowed in research and Government control laboratories, as well as 
in large manufacturing concerns. The raw materials and finished 
product, therefore, are discussed from the standpoint of adherence 
to the present specifications in force by the Ordnance Department. 

A. Testing or Raw Material. 

Both the raw materials used and finished product shall conform 
to Ordnance Department Specifications 450, dated February 28, 
1918, and Ordnance Department Specifications 451, dated August 
1, 1918, or subsequent revisions thereof. 

METHODS OF ANALYSIS FOR CELLULOSE. 

Moisture. — Weigh 5 to G grams in a large weighing dish with 
ground glass stopper. Heat for one and one-half hours at 105° C. 
Cool in desiccator and weigh. Loss in weight is calculated as 
moisture on sample taken. Save dried sample for determination of 
extractive matter. 

Extractive matter. — Place (weighed) sample in a Wiley or 
Soxhlet extractor and add sufficient redistilled ethyl ether for the 
extracting. Extract on the steam bath for three hours. Transfer 
the ether to a weighed beaker or glass evaporating dish and 
evaporate to dryness on steam bath. Heat for 30 minutes in an oven 

71 



72 MILITARY EXPLOSIVES. 

at 100° C, cool in desiccator, and weigh. Calculate per cent of ex- 
tractive matter on weight of dry cotton. 

Ash. — Weigh out about 1.5 grams of cellulose in a tared platinum 
or silica crucible. Moisten with strong nitric acid, then heat gently 
over Bunsen burner until acid fumes have disappeared, finally heat- 
ing to a red heat until all carbonaceous matter has been consumed. 
The crucible should be partly covered with a lid during the heating. 
Cool in a desiccator and weigh. Calculate the difference in weight 
as percentage on the dry weight of sample taken. 

Test for overbleach. — Boil 5 to 10 grams original sample with dis- 
tilled water. Filter. Concentrate the filtrate and test portions for 
chlorides, sulphates, and Ca. Use barium chloride to detect sul- 
phates. Use silver nitrate to detect chlorides (after acidifying 
slightly with nitric acid). 

The material soluble in potassium hydroxide solution will be de- 
termined by heating 2 grams of cotton, previously dried at 102-105° 
C, in a 250 c. c. glass or porcelain beaker with 100 c. c. of the caustic 
potash solution (10.0±0.1 per cent) for three hours at 100° C, or 
an equivalent strength of sodium hydroxide solution (7.14±:0.1 per 
cent) . Care must be taken to avoid concentration of the solution or 
undue oxidation of the cotton, due to the exposure of the alkali- 
soaked cotton to the air. After the heating is completed the cotton 
and solution are poured into a beaker containing 1 liter of distilled 
water, the alkali is neutralized with decided excess of acetic acid. 
The undissolved cotton is then filtered on to a weighed Gooch cru- 
cible having an asbestos mat, and thoroughly washed successively 
with hot water, alcohol, and ether. It is then rapidly dried to con- 
stant weight at 102-105° C. The loss in weight is then calculated 
as per cent. 

METHOD OF ANALYSIS FOR DIPHENYLAMIXE. 

Total di/phenylamine. — Bromination in acetic acid solution. From 
2 to 3 grams of sample is weighed into a beaker and dissolved in 
25 c. c. glacial acetic acid. A solution of bromine in acetic acid 
(1:2) is then added a drop at a time until a distinct yellow color 
persists after stirring. The beaker is covered and set aside for 15 
minutes at room temperature, during which time a distinct yellow 
color should remain. The beaker is then placed on a steam bath and 
heated for five minutes, at the end of which time there should be a 
yellow color. The beaker is set aside to cool and 150 c. c. water 
added. The beaker is placed on steam bath and heated till the hand 
can barely stand the heat and the precipitate is then filtered off and , 
washed five or six times with hot water, and dried to constant weight. 
The weight of precipitate multiplied by 0.3487, divided by the weight 



MILITARY EXPLOSIVES. 73 

of sample, and multiplied by 100 gives per cent of diphenylamine in 
original sample. 

Melting point. — Determine by method described under trinitro- 
toluene. The capillary tube should be somewhat larger than that 
used for trinitrotoluene and a thermometer which can be read accu- 
rately to 0.5° C. may be used. The melting point should be between 
51.5° and 53° C. 

Solubility in ether alcohol. — Dissolve 5 to 10 grams in an excess 
of ether-alcohol mixture (2:1). Filter through tared Gooch cru- 
cible. Wash thoroughly with fresh solvent. Dry at 100° C, cool in 
desiccator, and weigh. 

Water soluble. — Boil 10 grams of diphenylamine with 200 c. c. 
water for one hour in a flask fitted with reflux condenser. Cool to 
25° C. and let stand for one hour. Filter into a tared evaporating 
dish, run to almost dryness on a steam bath. Dry in desiccator over 
sulphuric acid and weigh. 

Aniline. — Stir about 1 gram of sample in 20 c. c. of chlorinated 
lime solution. This should not acquire a violet color. 

Reaction. — Should be neutral or slightly alkaline to litmus paper. 
Test by method described under trinitrotoluene for acidity. 

METHOD OF ANALYSIS OF MIXED ACIDS. 

The analysis of mixed acids involves the following operations: 

1. Titration with N/10 NaOH for total acidity. 

2. Determination of total HNO s by nitrometer. 

3. Evaporation of HN0 3 and titration of the residue for 
total H,S0 4 . 

4. Titration with N/10 KMn0 4 for oxides of nitrogen. 

5. Specific gravity. 

By calculation the values obtained in the above operations are 
reported as : 

1. Total H 2 S0 4 . 

2. Available HN0 3 . 

3. Total N 2 4 . 

4. H 2 0. 

The details of the operations and calculation are described below : 
1. Total acidity. — A sample of approximately 1 gram is run from 
a Lunge acid pipette into a 500 c. c. beaker containing 150 to 175 c. c. 
of standard N/10 NaOH. Add 3 to 4 drops of methyl orange indi- 
cator and complete the titration with the standard alkali. 

Correction for burette reading: For each °C. above the tempera- 
ture at which the solution was standardized subtract, for each °C. 
below this temperature add, 0.01 c. c. for each 35 c. c. of NaOH used. 



74 MILITARY EXPLOSIVES. 

Calculate the total acidity as per cent H 2 S0 4 . For this calculation 
use the formula — 

Per cent H 2 S0 4 =-q— 

in which 
n=number of c. c. (corrected) of N/1.0 NaOH used to titrate. 
f=factor to convert standard N/10 NaOH to H 2 S0 4 . 
S=weight of sample taken. 

2. Total HNO z . — Determine in Du Pont nitrometer. Use a sample 
of about 2 grams for spent acid, 1| gram for mixed acid, and 0.8 to 
0.9 gram for fortifying acid. The nitrometer reading divided by 
the weight of sample taken multiplied by 4.49807 (Log. 65303) gives : 
Per cent HN0 3 . 

3. Total H 2 S0 4 . — Convert total HN0 3 found by the nitrometer 
to H 2 S0 4 , by multiplying by 0.77814 (Log. .89106). Subtract this 
from the total acidity as H 2 S0 4 . The remainder is total H 2 S0 4 . As 
a check on this figure the following determination should be made : 

A sample of about 2 grams of mixed acid is run from a Lunge 
pipette into a large-sized porcelain crucible lid. Place the lid on 
the small hole of the steam bath and evaporate for one hour with 
good pressure of steam. Then add 1 c. c. of water, drop by drop, 
carefully avoiding any spurting. Tilt the lid from side to side to 
cause a flow of the liquid over the whole surface, and continue the 
evaporation for one-half hour. Then add another 1 c. c. of water 
and repeat the operation. This treatment serves to break up the nitro- 
sulphuric acid present, liberating the oxides which evaporate with 
the water. 

Transfer the lid to a 400 c. c. beaker containing 150 to 175 c. c. of 
N/10 NaOH and titrate exactly as described under total acidity. 
Calculate the acidity as H 2 S0 4 by the formula given above. 

4. Oxides of nitrogen. — Put about 200 c. c. of distilled water in a 
400-c. c. beaker and color it slightly with a small drop of N/5 
KMn0 4 . Then run into the water from a Lunge pipette about 10 
grams of acid, using a short piece of glass tubing connected to the 
tip of the pipette by a very short piece of rubber tubing and dip- 
ping below the surface of the water. When the sample has been 
added the additional tubing should be disconnected and dropped into 
the beaker. Titrate with N/5 KMn0 4 until a pink color persists 
for 10 minutes. The bulk of the KMn0 4 solution may be added at 
once and then make gradual additions as the color fades. A point 
will finally be reached when the color fades very rapidly, having just 
before this time persisted for several minutes with the addition of 1 
or 2 drops of solution. Beyond this point about one-tenth of the total 
amount used is required to complete the titration. It is unnecessary 



MILITARY EXPLOSIVES. 75 

to make corrections for slight errors in the burette readings or for 
temperature, as a considerable error is necessary to affect results. 

Calculate the percentage of N 2 4 from the volume of KMn0 4 
used and convert it to its equivalent in HN0 3 . Subtract this equiva- 
lent in HN0 3 from the total HN0 3 obtained in 3. The difference is 
actual HN0 3 . 

The actual HN0 3 plus one-half the N,0 4 calculated as HN0 3 is 
available HN0 3 . 

Formula for calculations: 

Per cent N 2 4 = n * f 
in which 

n = number of c. c. of N/5 KMn0 4 used to titrate, 
f = factor for converting to N 2 4 . 
S= weight of sample taken. 

To convert N 2 4 to its equivalent in HN0 3 multiply by 1.36966 
(Log. .13661). 

5. Water. — This is calculated by difference. The sum of the per- 
centages of H 2 S0 4 , HN0 3 , and N 2 4 substracted from 100 per cent is 
taken as water. 

Standardization of solutions.- — NaOH : This is made approxi- 
mately tenth normal. A large carboy is filled with distilled water 
which has previously been boiled to remove C0 2 and cooled in run- 
ning water. Dissolve in a portion of the water 4 grams of NaOH for 
each liter of water used, filter quickly through glass wool if neces- 
sary, avoiding much exposure to air. When the solution is compara- 
tively cool, add it to the water in the carboy, washing out the beaker 
with a portion of water taken out of the carboy before the soda was 
added. Mix the solution by blowing air through it which has been 
freed from C0 2 by passing it through a wash bottle of strong caustic 
solution. The mixing should be continued for about two hours. If 
the container is not too large, it may be mixed by shaking by hand. 
When thoroughly mixed, set the container in its place and connect 
with a wash bottle containing strong NaOH solution to protect it 
from the C0 2 of the air. 

The solution so prepared should be standardized carefully at least 
once a week against N/10 H 2 S0 4 and HC1. A standard H 2 S0 4 of 
about 90 per cent strength should be kept in a double-sealed bottle 
in a desiccator and the standard alkali titrated once a month against 
a weighed sample of this acid. 

The values for the standard acid solutions should be based on 
gravimetric results. The standard N/10 H 2 S0 4 and HC1 should be 
standardized at least once a month by the following methods : 

For N/10 H 2 S0 4 : Standardize at 25° C. or make corrections of 
0.01 c. c. per °C. for each 35 c. c. above or below 25° C. Make dupli- 



76 MILITARY EXPLOSIVES. 

cate determinations, using 50 c. c. for each determination. Dilute to 
200 c. c. Add a few drops of dilute HC1. Heat to- boiling. Add 
slowly with stirring 7 to 8 c. c. of 10 per cent BaCl 2 solution. Con- 
tinue boiling a few minutes. Set on steam bath until the precipitate 
becomes granular and settles to the bottom, leaving a clear solution. 
Filter while hot through a Gooch crucible containing a mat of acid- 
treated and ignited asbestos. Wash well with hot water, dry, and 
ignite for one-half hour at a good red heat. Cool in desiccator and 
weigh. Calculate the weight of the precipitate of BaS0 4 to H,S0 4 
per liter of solution. Find the normality factor of the solution by 
dividing this weight by 49,045 and express the result to 4 places of 
decimals. 

For N/10 HC1: Standardize at 25° C. or make corrections as for 
H 2 S0 4 . Make duplicate determinations, using 30 c. c. for each de- 
termination. Add 20 c. c. of water and a few drops of HN0 3 . Then 
add, drop by drop, 6 c. c. of a fresh 10 per cent A g N0 3 solution with 
constant stirring. After precipitation is complete wash down the 
sides of the beaker with a thin stream of water from a wash bottle. 
Heat to about 70° C, stirring constantly, then set away in a dark 
place over night, On the following day filter through a white-ribbon 
S. & S. filter paper and wash with warm water slightly acidified 
with HN0 3 until all trace of A g N0 3 is removed. Dry at 100° C, 
transfer the precipitate to a glazed paper and ignite the filter paper 
in a weighed porcelain crucible. After carbon has been burned off, 
add a drop or two of HN0 3 and HC1. Evaporate to dryness, trans- 
fer precipitate to crucible and heat to incipient fusion, cool in desic- 
cator and weigh. Calculate the weight of A g Cl to HC1 per liter 
of solution. Find the normality factor of the solution by dividing 
this weight by 36.47 and express the result to 4 places of decimals. 

If it is desired, a Gooch crucible with an asbestos mat may be 
substituted for the filter paper if the mat is thick and compact, and 
the operator can check results by this method with those by the 
method described above. 

ALCOHOL. 

Test for aldehyde. — Prepare the following solutions : 

(a) Weigh accurately 9 grams silver nitrate, c. p., and dissolve 
it in 100 c. c. of water. 

(b) Weigh 9 grams of sodium hydroxide and dissolve it in 100 
c. c. of water. 

(c) A solution of ammonium hydroxide, specific gravity 0.90. 
These three solutions should be kept in separate bottles (a) in a 

dark place. For the test put 1 c. c. of silver nitrate solution in a 
small graduate, add 1 c. c. of sodium hydroxide solution and then 
1 c. c. of ammonium hydroxide solution, or until the precipitate is 



MILITARY EXPLOSIVES. 77 

just dissolved. Then put 10 c. c. of the alcohol to be tested in a clear 
glass-stoppered bottle, add 10 c. c. of distilled water and 1 c. c. of the 
mixture prepared in the small graduate. Shake and allow to stand 
for one hour in a dark place. Then filter and test the clear filtrate 
for unreduced silver, by adding a solution of sodium chloride. If 
silver chloride is precipitated the alcohol contains less than the 
maximum allowable amount of aldehyde. 

The specific gravity is determined by means of a Westphal balance. 

Acidity. — Measure 50 c. c. of alcohol into an Erlenmeyer flask, 
add 3 to 4 drops phenolphthalein as an indicator and titrate with 
N/100 KOH solution. Calculate acidity as acetic acid. 

Formula: Per cent acidity= c-cKOHX0.006Xl00 

SOXspecifie gravity. 

The acidity should not exceed 0.01 per cent. 

ETHER. 

Specific gravity. — Determine specific gravity by the Westphal 
balance. 

Acidity. — Measure 50 c. c. of alcohol into an Erlenmeyer flask, 
add three drops phenolphthalein solution and titrate to faint pink 
with N/100 KOH. Then add 50 c. c. of ether and titrate again to 
faint pink. Calculate acidity as acetic acid by the formula : 

Per cent acidity- cc.KOHx0.006Xl0 
J 50 X gravity. 

DU PONT NITROMETER. 

Theoretical. — The Du Point nitrometer is a modification of the 
Lunge nitrometer and is devised to avoid the necessity of making 
the usual correction for temperature and barometric pressure which 
must be calculated with every gas measurement. The principle of 
the apparatus is to inclose a known volume of air at such a pressure 
that it takes up exactly the volume which it would occupy at 20° C. 
and 760 mm. pressure. If the same pressure and temperature are 
then applied to another volume of gas this will also take up the 
volume which it would occupy at 20° C. and 760 mm. pressure. The 
volume of air is kept in a " compensating tube " which is in connec- 
tion with the reading tube of the nitrometer. When it is desired to 
read the volume of a given quantity of NO gas at 20° C. and 760 
mm. pressure, the level of the mercury in the " compensating tube " 
is brought to the mark at which the air within the tube occupies 
the space it would occupy at 20° C. and 760 mm. pressure, the level 
of the mercury in the reading tube is brought on a level with this 
same mark and the reading made. The reading tube on the Du Pont 



78 



MILITARY EXPLOSIVES. 





OUPONT NITROMETER 



nitrometer is graduated to read directly to per ^ent of nitrogen when 
a 1 gram sample is used. 

To set up a Du Pont nitrometer. — The various tubes are arranged 
on the nitrometer rack in order shown in the accompanying sketch ; 

25 c. c. of 95 to 96 per cent H,S0 4 
are then placed in No. 2 and a 
quantity of air drawn in through 
the stopcock. The stopcock is 
then closed and the bulk shaken 
vigorously to dry the air. The 
shaking is repeated several times 
at intervals of from 10 to 15 min- 
utes. When the air is judged to be 
thoroughly dry, 2 and 4 are con- 
nected and the dry air run into 4 
until, with the stopcock of 3 open 
and the mercury in 3, 4, and 5, on 
the same level, the reading in 3 is 
about 12.50. No. 4 is then sealed 
with a small blowpipe flame. 
Another portion of air is then desiccated in 2 and transferred to 3 
until, with the mercury in 3, 4, and 5 on the same level, the reading 
in 3 is about 12.50. It is not necessary that these gas volumes be exact 
or equal. The small manometer, A, is then filled with H 2 S0 4 and at- 
tached to 3. The apparatus is then left to come to constant tempera- 
ture. The mercury in 3, 4, and 5 is then adjusted so that the air in 
3 is under atmospheric pressure as shown by the acid in A. The 
reading is taken on the graduated scale on 3. The temperature and 
barometric pressure are noted at the same time. From these readings 
the volume of air in 3 is calculated at 20° C. and 760 mm. pressure 
by the gas laws which are expressed by the equation: 

V:V'=P':P 
V:V'=T:T' 

in which 

Vr=volume at 20° C. and 760 mm. 
V'= volume at the observed tem- 
perature T' and pressure P'. 

From these is derived the equation : 



V = V; 



p'X.293 



X 



l-(0.00018t / ) 



760 X (273 + T') 1 - (0.00018 X 20) 
The last term of the equation represents the correction to be ap- 
plied for the coefficient of expansion of mercury in the barometer 
where t' equals temperature of the barometer. When V has been 
calculated, the mercury in 3, 4, and 5 is adjusted so that, with the 



MILITARY EXPLOSIVES. 79 

mercury in 3 and 4 on a level, the mercury in 3 marks the calculated 
volume of air. The height of the mercury in 4 is then marked by a 
strip of paper pasted on the tube. This is taken as the standard 
volume with which every volume of gas to be measured is compared. 

Standarization with C. P. KNO z . — Take a sample of C. P. KN0 3 
which has been recrystalized three times from alcohol, grind it fine 
and dry for one and one-half to three hours at 150° C. Then weigh 
out in a small weighing bottle exactly 1 gram and transfer it to the 
nitrometer (for details see "Determination of nitrogen"), dissolving 
the KN0 3 in the nitrometer cup with 20 c. c. 95 per cent plus or minus 
0.3 per cent H 2 S0 4 . With the lower stopcock of the generating bulb 
open and the mercury bulb low enough to give a reduced pressure in 
2, gently shake the generating bulb until the larger portion of gas 
has been generated. Then raise 2 until the mercury drops nearly to 
the lower shoulder, close the lower stopcock and shake vigorously 
for three minutes. Replace on the rack, open the lower cock, and let 
stand for several minutes. Then repeat the shaking for an additional 
three minutes, adjusting the mercury as before. Finally transfer the 
gas to 3, adjust 3, 4, and 5 so that the level of mercury in 3 and 4 is 
about on the level and allow to stand 20 minutes. Then carefully ad- 
just the mercury levels with leveling device and take the reading in 3. 
This should be 13.85 per cent. 

Standardization by a test blend. — This standardization is run in a 
way similar to the above except that a blend of nitrocellulose which 
has been carefully tested on a standardized nitrometer is used. This 
method is somewhat more convenient than the method with KN0 3 
because the nitrocellulose is more easily broken up in the nitrometer 
than KN0 3 . Whenever a doubt exists, however, the standardization 
must be carried out with KN0 3 . 

B. Testing of Nitrocellulose. 

Ether-alcohol- insoluble material}. — The percentage of ether-alco- 
hol-insoluble material in nitrocellulose may be determined as fol- 
lows: Soak 1 gram of the dry sample for two hours in 50 c. c. of 
95 per cent alcohol in an Erlenmeyer flask. Then add 100 c. c. of 
ethyl ether, shake and allow to stand overnight. On the following 
morning the mixture is shaken thoroughly and transferred with 
Avashing by 80-100 c. c. of fresh ether-alcohol mixture (2:1) to a 
specially constructed solubility tube of the following dimensions: 
Total length, 21 inches; inside diameter, 1.35 inches; the lower end 
constricted for a distance of 2 inches to an inside diameter of 0.3 
inch and graduated in one-tenth c. c. to 10 c. c. The constricted 
portion should be tapered gradually from the large part of the 
tube and the graduations should extend to the top of the shoulder 
thus formed. After standing for seven hours in the solubility tube 



80 MILITARY EXPLOSIVES. 

the volume occupied by the insoluble and semisoluble matter is read 
in c. c. from the scale on the tube. This number (of c. c.) multiplied 
by 0.5 is the percentage of ether-alcohol-insoluble matter as noted in 
the specifications for smokeless powder. 

The official temperature for this determination shall be 15.5° C. 
and in case of doubt or for greater accuracy the complete determina- 
tions shall be made at this temperature, the solvents being brought 
to this temperature before their addition to the sample. The insolu- 
ble material should not exceed 5 per cent. If it exceeds 5 per cent 
(10 c. c.) this method must be discarded and special quantitative 
methods devised. 

Heat test 65.5° C. with potassium-iodide starch paper. — The sam- 
ple shall be pressed in a clean cloth or wrung in a wringer if it con- 
tains a large excess of water. The cake shall be rubbed up in a cloth 
until fine, taking care that it does not come in contact with the hands, 
spread out on clean paper trays and dried in an air bath at 35° to 43° 
C. just a sufficient length of time to reduce the moisture to that 
amount which will give a minimum heat test, this amount being from 
1.5 to 2 per cent. 

During this time the tray is taken out several times and the nitro- 
cellulose is "rubbed up" with a piece of tissue paper spread over 
the back of the fingers. When the nitrocellulose begins to stick to 
the tissue paper, due to static electricity which is developed when 
dry nitrocellulose is rubbed, take a sample of 1.3 grams and put in 
KI starch test tube, shaking it down to occupy about If inches in the 
tube. These tubes for this test are standard 5| inches long, one-half 
inch internal diameter, and five-eighths inch external diameter, closed 
by a clean cork stopper fitting tightly, through which passes a tight 
fitting glass rod with platinum holder for the paper. Continue the 
drying and rubbing, taking samples at appropriate intervals of two 
to five minutes until the sample on the tray is completely dry and 
five samples have been collected. This series of samples is called 
the " moisture series " and is taken in order that samples may be run 
containing varying percentages of moisture. 

If, as sometimes happens in dry weather, the moisture has been 
reduced to less than 1.5 per cent, the sample shall be placed in a moist 
atmosphere for a time not exceeding two hours until the required 
moisture percentage is obtained. The whole time of drying and 
making the test shall not exceed eight hours. 

When these five samples have been collected they are prepared for 
the test as follows: Select a clean, fresh cork stopper which just fits 
the tube. Perforate it and introduce a short length of closed glass 
tube into the lower end of which a small piece of platinum wire has 
been fused. Burn off the platinum wire in a flame. Then fix on it 
a strip of KI starch paper 1 inch in length, three-eighths inch wide. 



MILITARY EXPLOSIVES. 81 

This should not be touched with the fingers. Draw across the paper 
near its upper end a glass rod which has been dipped into a solution 
composed of one part glycerine and one part distilled water. Then 
fit the stoppers so prepared into the test tubes containing the samples 
to be tested. Immerse the five tubes in the specially prepared heating 
bath, which is kept at a temperature of G5.5° C. ± 1° C Then note 
carefully the appearance of the first faint yellow line at the lower 
edge of the moistened portion of the test paper. This discoloration 
is to be greater than that obtained at the same time by a blank test. 
The tube giving this color first is taken as the test for the lot. This 
time shall be not less than 35 minutes. 

Standard test papers will be used and will be furnished by the 
department to manufacturers. 

The standard water bath holds 10 tubes and is made long and 
narrow to reduce to a minimum the upper portions of the tubes. 
These tubes are immersed in the bath to a standard depth of 2.25 
inches. 

Test at 135° C. — A sample of nitrocellulose is laid out in paper 
trays and dried for four or five hours at 42° C., or is dried overnight 
at room temperature and then further dried one-half hour at 42° C., 
after which 2.5 grams are pressed into the lower 2 inches of each of 
two tubes of heavy glass, about 290 mm. long, 18 mm. outside di- 
ameter, and 15 mm. inside diameter, closed with a cork stopper 
through which a hole 4 mm. in diameter has been bored. A piece of 
standard normal methyl violet paper, 70 mm. long and 200 mm. wide, 
is placed in each tube, its lower edge 25 mm. above the cotton. When 
the constant temperature bath has been carefully regulated at 134.5° 
C, plus or minus 0.5 C, these tubes are placed in the bath so that not 
more than 6 or 7 mm. of length projects from bath. Examination 
of the tube is made each five minutes after 20 minutes have elapsed 
by withdrawing about one-half its length and replacing quickly. 
When salmon pink is obtained between examinations, after 25 
minutes and before 30 minutes, a 30-minute record shall be allowed 
the sample. The methyl violet test paper in either tube shall not be 
completely turned to standard salmon pink in less than 30 minutes. 

The test is continued for five hours and no explosion should occur 
in that time. 

The bath must be placed in a good light with a suitable back- 
ground. 

There shall be no failure of either of the tubes. 

The standard normal methyl violet papers will be furnished by 
the department. 

Determination of nitrogen. — A sample of approximately 1 gram 
is taken. This is weighed in a small weighing bottle, dried one and 
one-half hours at 100° C, cooled in a desiccator, reweighed and 
132569—19- — S 



82 MILITARY EXPLOSIVES. 

transferee! to the cup of the nitrometer. Measure out 20 c. c. of 95 
per cent plus or minus 0.3 per cent H,S0 4 . Pour a portion of it into 
the - cup and wash the nitrocellulose into the generating bulb. Kinse 
out the weighing bottle with successive portions of acid, pouring into 
the nitrometer cup each time and running into the bulb. If the nitro- 
cellulose is very dusty, it is best to dissolve it in the weighing bottle 
before transferring. Each successive portion of acid poured into the 
cup should be directed by means of a small stirring rod so that it 
rinses down the sides of the cup. When all is in the bulb, the NO 
gas is generated just as described under standardization. The gas 
is transferred to the measuring tube and the reading taken after 
standing 10 or 15 minutes. The reading is corrected for the sample, 
above or below 1 gram, the result being the percentage of nitrogen 
in the sample. If exactly 1 gram of sample is employed no correc- 
tion is necessary. 

Ash. — Weigh approximately 1 gram of sample in a tared crucible. 
Moisten with a small quantity of concentrated nitric acid and digest 
for two or three hours on the steam bath. Then place on a triangle 
and heat with a Bunsen burner, very cautiously at first to avoid 
loss. Finally place crucible in an inclined position, partly cover 
with lid and heat strongly over the blue flame of a Bunsen burner 
until all carbonaceous matter has disappeared. Cool in desiccator 
and weigh. 

Acetone insoluble material. — This (heretofore-called " organic resi- 
due ") is obtained by dissolving 1 gram of nitrocellulose in 100 c. c. 
of pure acetone in an Erlenmeyer flask and then transferring to a 
" solubility tube " which is described in paragraph headed " Ether- 
alcohol-insoluble material " and continuing as prescribed in that 
paragraph. 

C. Testing of Smokeless Powder. 

Ten normal grains will be taken and both ends cut off at right 
angles to the length until — 

diameter _ 
length 

These pieces are accurately measured for length and then slowly 
compressed between parallel surfaces until the first crack appears. 
The pressure is then removed and the grain again measured. The 
decrease in length necessary to crack the grain is calculated to per 
cent of original length. The average compression must not be below 
35 per cent. In case of failure in this test 20 more grains are tested, 
and if the average compression of the total 30 grains is below 35 per 
cent the powder will be rejected. Grains accidentally abnormal in 
shape or containing obvious flaws will not be used for this test. 



MILITARY EXPLOSIVES. 



83 



Gravimetric density. — Weigh accurately the amount of powder 
required to fill box exactly 1 foot in every dimension, inside measure- 
ments. Report as pounds and decimal fraction of pounds. 

Specific gravity. — For 3-inch field gun and smaller calibers, deter- 
mine by the following method : Place an accurately weighed sample of 
15 to 20 grams, using whole grains, in a standardized specific gravity 
bottle. Cover with boiled distilled water and hold under a vacuum 
not less than 500 mm. until all air is displaced or approximately 20 
minutes. Fill the bottle with boiled distilled water at 15.5° C. and 
weigh. Subtract the weight of the bottle plus powder. This gives 
the weight of water in the bottle. The difference between this weight 
and the weight of water in the bottle when it was first weighed with 
the sample of powder represents the weight of water displaced by 
the powder. 

Measurements. — Thirty grains will be selected at random and 
measured for length, diameter, perforation, and (inner and outer 
thickness) webs. 

For grains having seven perforations the outside diameter (D) of 
the grain shall be about 10 times the diameter (d) of the perforations, 
and the length (L) from 2.1 to 2.5 times the outside diameter. For 
grains having a single perforation the outside diameter (D) shall 
be about three times the diameter (d) of the perforation, and the 
length (L) about three times the outside diameter. The dimensions 
(L and D) of at least 30 grains specified must comply with the re- 
quirements for uniformity as per table. 



Dimensions. 


Mean variation of individual dimen- 
sions from mean dimensions, ex- 
pressed in per cent of mean dimen- 
sions. 


Permitted. 


Desired less than— 


L 


5.0 
2.5 


1.0 
5 


D 





For grains having seven perforations six measurements of the out- 
side-web thickness (Wo) and of the inside-web thickness (Wi) will 
be made from the six outside holes for each of the 30 grains, and the 
two sets of 180 measurements will be averaged to obtain the mean 
outside and inside webs. The powder shall have the inside- web 
thickness as nearly as practicable about 5 per cent less than the 
outside-web thickness. The outside-web thickness may exceed the 
inside-web thickness by 15 per cent and may be less than the inside- 
web thickness by 5 per cent. The percentages are calculated on the 
average web thickness. 

For grains having a single perforation take the greatest and least 
web measurements of each of the 30 grains. Neither the average of 



84 MILITARY EXPLOSIVES. 

the 30 least measurements nor the average of the 30 greatest measure- 
ments should differ more than 15 per cent from the average of the 
entire 60 measurements, which is the average web of the powder. 

Approximately one-third the length of each powder grain is cut 
from each end of 30 grains. The remaining one-third of the grain or 
middle portion of the original grain is "faced" and the end surfaces 
made exactly parallel. Care must be taken to have clean perforations 
and edges. A microscope having a micrometer stage attachment is 
used for obtaining the measurements. 

The grains are measured three times across for seven-perforation 
powder and once across for single-perforation grains. 

The number of measurements taken on seven-perforated powder 
are therefore as follows : 

Three measurements of diameter (D) ; six measurements of out- 
side- web thickness (Wo) ; six measurements of inside-web thickness 
( Wi) ; three measurements of the center hole are taken on each of the 
30 grains and six measurements of other perforations on the same 
number of grains. 

Grains per pound. — This should be very accurately determined b} r 
weighing an appropriate quantity and counting the grains, calcu- 
lating from this data the number of grains per pound. If the weight 
is taken in grains, calculate the number of grains per kilogram and 
divide by the factor 2.20462. This gives grains per pound. For .30 
caliber powder, weigh 2 grams. For other sizes of powder up to 
4.7-inch howitzer, weigh 1 pound. All counts should be made in 
duplicate samples. The average of the two is reported. 

Burning surface. — Use the following formula in which — 

D=diameter of the grain in inches. 
d= diameter of perforation in inches. 
L= length of grain in inches. 
N=number of grains per pound. 

Formula for powder containing seven perforations : 

Burning surface=ixN[D 2 -7d 2 -f 2L(D7d)] 

Formula for powder containing one perforation : 

Burning surface=!zN(D-f-d) (D-d+2L) 

Formula for sliverless grains : 

Burning surface=N[2[(A-7A 1 )6A 2 ]+61L+27:dL] 

A=area of hexagon drawn from reentrant angles. 
A x r=area of perforation. 

r=radius of circle drawn from center of outside 
perforation and 1 the arc. 

l=.0175XrXE. 

E=included angle of arc. 



MILITARY EXPLOSIVES. 85 

Determination of moisture and volatiles. — Select at least 10 grains 
and chip several thin shavings from each grain, discarding the end 
portion. If the powder is too small to chip conveniently, whole 
grains may be used. The chipping should be done as rapidly as 
possible and chips dropped quickly into a weighing bottle to avoid 
loss of volatiles from the freshly cut surfaces. Quickly weigh ap- 
proximately 1 gram of these chips into a low form 250 c. c. "volatile 
beaker" which has been thoroughly cleaned, desiccated, and weighed. 
Use this weight of beaker in final calculations. Add 50 c. c. of redis- 
tilled alcohol and 100 c. c. of redistilled ether. Place beaker under 
a tight bell jar until solution is complete. This usually requires one 
to two days. The mixture should be stirred occasionally to hasten 
solution. More ether should be added if much of the ether has been 
evaporated and solution is not yet complete. Residue determinations 
should be made on ether, alcohol, and water used in the process and 
corrections applied to the final weight of the precipitate. 

When all lumps have disappeared, place the beaker on the steam 
bath and evaporate off a portion of the ether. The amount of ether 
that is evaporated here is very important, since it determines the 
nature of the nitrocellulose which is precipitated in the next step. If 
too little is evaporated, a fine sandy precipitate is obtained and the 
contents of the beaker are likely to " bump" in drying. If too much 
is evaporated, a gummy precipitate is obtained which can not be 
dried completely. A gummy precipitate should be avoided. A fine 
flaky precipitate will give the best results. The amount to be evapo- 
rated can be learned only by practice. Approximately 1| to 2 inches 
of solution should be in the beaker when the nitrocellulose is precipi- 
tated. 

When the proper point is reached, take the beaker off of the steam 
bath and add 50 c. c. of distilled water which precipitates the nitro- 
cellulose. A precipitate of the proper mixture may be obtained in 
determination by adhering closely to the following procedure: 
While still warm add, with stirring, 5 c. c. of distilled water from a 
graduate containing 50 c. c. Stir until precipitate has been disinte- 
grated. Add about 5 c. c. more and repeat above operation. If the 
precipitate appears to be thick and heavy, add, with stirring, about 5 
c. c. of ether at a time until precipitate becomes light and flaky. 
Then add slowly, with constant stirring, the remainder of 50 c. c. 
of water. 

After precipitation is complete the beaker is replaced on the 
steam bath and stirred carefully until the bulk of the ether has 
been evaporated and there is no longer danger of " bumping." In 
stirring avoid touching the sides and bottoms of the beaker as 
much as possible. When there is no longer signs of foaming, the 



86 MILITARY EXPLOSIVES. 

beaker is suspended in the bath by means of specially constructed 
wooden blocks and allowed to evaporate to dryness. Do not allow 
to remain on bath any longer than is actually necessary for drying. 
On removal from the bath the precipitate should be white or grayish 
white. A yellow or greenish yellow color indicates that the pre- 
cipitate has been on the bath too long. Then wipe the outside of 
the beaker clean and put it in an oven at 100° C. quickly. Before the 
desiccator is opened, adjust weights on the scale pan to balance the 
beaker as nearly as possible. If more than 10 seconds are required 
to get the weight of the beaker, it will have absorbed enough mois- 
ture from the air to seriously affect the results and should be put 
back in the 100° C. bath for 30 minutes more and the weighing re- 
peated. This second check weighing is advisable in all cases where 
accurate work is important. 

The difference between the weight of the sample taken and the 
weight of the precipitated nitrocellulose is calculated as moisture 
and volatiles. Deduct 0.01 per cent from this result to allow for 
the volatilization of diphenylamine in the powder. If the powder 
contains more or less than 0.4 per cent of diphenylamine, make the 
proper correction, assuming that 25 per cent of the diphenylamine 
volatilizes. 

Diphenylamine in smokeless powder. — Put 5 grams of powder in 
a 250 c, c. beaker. Pour 30 c. c. of concentrated HN0 3 over it. 
Cover with a watch glass and set on steam bath until the powder is 
completely dissolved. Continue the heating for one-half to one hour 
after solution has taken place to insure complete decomposition of 
the nitrocellulose. Then cool and pour into another beaker contain- 
ing about 100 c. c. of cold distilled water, stirring constantly during 
addition. Wash out the beaker and watch glass into second beaker, 
stir vigorously, and set on the steam bath until the precipitate col- 
lects in a flocculent form and the solution is a clear yellow color. 
Cool, filter through a weighed Gooch, dry at 100° C, and weigh. 
Extract with acetone. Dry and weigh again. The loss equals the 
nitrodiphenylamine formed. Multiply by the factor 0.40576 to con- 
vert to diphenylamine. 

This method is much more rapid than the bromination method and 
gives good results, which are somewhat higher than the latter 
method. 

Determination of alcohol in poioder. — Weigh 100 grams sliced pow- 
der (unnecessary to slice 3-inch or smaller) into 1,000 c. c. distilla- 
tion flask. Connect with a condenser and cork the neck tightly with 
a rubber stopper that has a wide-mouthed separatory funnel through 
it. Add 25 to 50 c. c. H 2 and 25 c. c. NaOH (30 to 40 per cent) and 
warm gently. At this stage great caution is necessary. When vio- 



MILITARY EXPLOSIVES. 87 

lent decomposition has ceased, add NaOH from time to time until 
total decomposition of powder has been effected. When this stage 
is reached, increase the heat and distill off 150 to 175 c. c. of liquid, 
replacing with H 2 lost from time to time by distillation. 

The distillate is neutralized or made slightly acid with H,S0 4 and 
100 c. c. redistilled. Bring to 20° C. and read the refractine index 
at 20° C. with Zeiss immersion refractometer. From the Zeiss read- 
ing the amount of alcohol may be found by reference to tables. 

Test at 135° C. — This test is run on all powders. Duplicate tests 
should be made. Large mixed grains are turned down on a lathe 
until they fit snugly into the regular 135° test tube. 

The test will be made on five samples in exactly the same way as for 
nitrocellulose, the powder being as nearly in whole grains as is consist- 
ent with the standard weight of 2.5 grams. No sample shall turn the 
normal methyl violet paper to standard salmon pink in less than one 
hour, nor shall any sample explode in less than five hours. Examina- 
tion of the tubes is made every five minutes. When the salmon pink 
is established between the observations at the end of 35 minutes and 
at the end of 60 minutes, a 60-minute test shall be allowed. The 
end point is established at the end of the five-minute period during 
which the salmon-pink color develops in the normal methyl violet 
paper. 

Moisture. — To obtain the amount of moisture in water-dried pow- 
ders, a sample of at least 5 whole grains of not less than 20 grams 
will be dried for six hours at 100° C.±2° C. at atmospheric pressure, 
cooled in a desiccator, and the resultant loss of weight determined 
by weighing. This loss will be considered as moisture, and the differ- 
ence between this figure and that of the total volatiles by precipita- 
tion will be considered as residual solvent. 



CHAPTER V. 

COMPOUND PROPELLANTS. 

So far there has been considered only the so-called " straight nitro- 
cellulose " powders, that is, those powders which do not contain either 
inorganic nitrates or high explosives. The propellants yet to be 
considered are those which are mixtures of nitrocellulose and nitro- 
glycerin, nitrocellulose, and inorganic nitrates, such as barium ni- 
trate and potassium nitrate, and mixtures of charcoal, sulphur, and 
potassium nitrate. 

SrORTING BALLIST1TE AND INFALLIBLE POAVDER. 

This explosive is used primarily as a propelling charge for shot- 
gun and Stokes trench mortar. Instead of being in the form of a 
cylinder, as is the case with .30-caliber rifle powder or cannon 
powder, it is cut in the form of square flakes or discs of approxi- 
mately 0.005 inches in thickness. 

The manufacture of sporting ballistite is concerned chiefly with 
the proper solution and incorporation of soluble nitrocellulose in 
nitroglycerin in the proportion of 60 per cent of the former to 40 
per cent of the latter. By mixing the soluble nitrocotton and nitro- 
glycerin in hot water a partial colloid is formed which is similar 
in certain respects to the colloid obtained when nitrocellulose is dis- 
solved in an ether-alcohol mixture. The water is then expressed 
from the mass by passing the colloid under rollers which are heated 
to about 40° C. This rolling operation is repeated until a uniform 
mixture of nitrocotton and nitroglycerin is obtained. It is finally 
cut into square flakes, then coated and blended in the usual manner. 

The inspection of ballistite consists only of stability tests : 

(a) The finished powder shall give a potassium iodide starch 
paper test of 15 minutes at 82.2° C. 

(b) 120° C. fume test : A sample of the powder which has been dried 
at ordinary laboratory temperature overnight shall be used for this 
test. There is placed in each of two tubes of heavy glass, which are 
about 290 mm. in length, 18 mm. outside diameter, and 15 mm. inside 
diameter, 2.5 grams of the material. When the constant temperature 
bath has been regulated at 120° C, these tubes are placed in the bath 
so that not more than 6 or 7 mm. of the tubes project from the bath. 
Examination of the tubes is made by withdrawing about one-half 
their length and replacing quickly eveiw 5 minutes. The test shall 



MILITARY EXPLOSIVES. 89 

be complete when the fumes fill the tubes. The powder shall give a 
fume test of not less than 15 minutes at 120° C. 

The storage of ballistite powder is maintained under the same 
conditions as nitrocellulose smokeless powder. 

e. c. POWDER. 

This propellant is generally used for the loading of blank car- 
tridges and consists of colloided nitrocellulose granulated with in- 
organic nitrates. The main point observed in manufacture is the 
proper incorporation and mixing of all ingredients. This process is 
usually conducted by means of a wheel mill in a manner somewhat 
similar to that used for black powder and reworked powder. Nitro- 
cellulose of approximately 12.9 per cent nitrogen is mixed with about 
10 per cent of a mixture of potassium nitrate and barium nitrate, to- 
gether with a small amount of diphenylamine and a pink coloring 
matter, and the product granulated by a mixture of water and a 
suitable solvent, in such manner that it forms small rounded grains. 
The nitrocellulose in these grains is only partially colloided, acting 
as a binding material and hardening the surface of the grains. 

INSPECTION. 

Granulation. — About 95 per cent shall stay on a 40-mesh screen, 
and not more than 2 per cent shall pass a 60-mesh screen. The pow- 
der shall be stable to the following heat tests : 

(a) K. I. starch paper test: A weight of 1.3 grams shall be taken 
and tested in the same way as .30-caliber powder. It shall give a test 
of not less than 35 minutes. 

(b) Heat test at 135° C. : A weight of 2.5 grams shall be taken 
and tested in the same way as .30-caliber powder. It shall not turn 
normal methyl violet paper salmon pink in less than 25 minutes, nor 
explode in less than 4 hours. 

The remaining nitroglycerin and nitrocellulose powders, used for 
military purposes; namely, pistol and revolver powders, bull's-ey 
powder, military rifle Nos. 22 and 34, improved military rifle Nos. 
17, 23, and 25 will not be discussed in this paper, inasmuch as the 
processes of manufacture can not be described without disclosing in- 
formation regarded by the manufacturers as confidential. 



CHAPTER VI. 
BLACK POWDER. 

GENERAL. 

European history contains references to black powder as early as 
1250 A. D. Roger Bacon in 1264 performed the first recorded ex- 
periments with this material and shortly after this time it was in- 
troduced as a propelling charge for the fourteenth century bom- 
bard. Authorities differ upon the subject of the origin of black 
powder. It has been attributed severally to the Chinese, Arabs, 
and Hindus. It is certain that the alchemists of mediaeval days 
were familiar, to a certain extent, with the properties of the mix- 
ture of saltpeter, sulphur, and charcoal. Certain authorities regard 
Berchtolcl Schwarz as the inventor. To him, at any rate, belongs 
the credit of being the first (1313 A. D.) recorded user of this ma- 
terial in the propelling of stones from a gun. Powder was first used 
in a meal state. Later camphor was added to prevent crumbling. 
Graining or granulating is first recorded in 1425, resulting in a 
stronger and more uniform powder. Classification of the grains by 
screening is reported by the French in 1525. Black powder grad- 
ually replaced all other devices as a propel] ant, until 1870 it was 
practically the only propellant used. Its present military use is 
practically confined to the following : 

First. Ignition charges. 

Second. Base charge or expelling charge for shrapnel shell. 

Third. Manufacture of primers and fuzes. 

Fourth. Saluting and blank-fire charges. 

Fifth. For time-train rings and combination fuzes. 

Sixth. For mixtures with other kinds of propellant powders for 
use in small arms ammunition. 

It is thus seen that in its former function as a propellant black 
powder has been superseded almost entirely, having been replaced 
by smokeless powder. Among some of the factors which may be 
mentioned as responsible for effecting this change are : 

First. A large quantity of solid residue after the ignition of a 
charge. 

Second. The volume of black smoke caused by the presence of a 
large quantity of noncombustible material. 

Third. The relatively great speed of erosion of the gun barrel 
due to the high temperature of combustion. 
90 



.MILITARY EXPLOSIVES. 91 

Fourth. Rapid deterioration when exposed to atmospheric con- 
ditions due to its hygroscopic tendency. 

On the other hand the manufacture of black powder is not tech- 
nically complicated. 

Owing to its sensitiveness unusual precautions must be observed 
in the manufacture. 

MANUFACTURE. 

Black powder is a mechanical or physical mixture of potassium 
nitrate, charcoal, and sulphur in the approximate proportions of 
75, 15 and 10, varying percentages being used with varying effects. 
The saltpeter and sulphur should be of a very high grade commer- 
cial quality, should be practically free from chlorides and chlorates, 
and for practically all grades, the percentage of perchlorate should 
not exceed 0.5 per cent. Charcoal should be obtained from burn- 
ing of peeled willow and alder, excepting for saluting and blank- 
fire powders, for which charcoal made from hard woods is used. 
Depending upon the use to which the particular grade is to be put 
the percentage composition of the finished material is altered as 
necessity demands. It has been found, for instance, that by increas- 
ing the percentage of saltpeter the rate of burning is increased; by 
increasing the percentage of charcoal the rate of burning is de- 
creased. Extensive incorporation improves the quality and uni- 
formity. 

Purification . of saltpeter is obtained by means of repeated re- 
crystallization, the formation of large crystals being prevented by 
continuous agitation of the saltpeter liquor. 

PROCESS. 

The sulphur and charcoal in the proportions specified are pul- 
verized at the same time in a ball mill, which consists of a revolving 
steel cylinder in which iron or steel balls do the crushing or grinding. 
This pulverized material is mixed either with pulverized saltpeter 
or stirred into a saturated solution of saltpeter, depending on the 
plant equipment. 

There are three methods of mixing: 

First. The French method, which is rarely used in this countrv. 
The pulverized saltpeter, charcoal, and sulphur are mixed and in- 
corporated in a ball mill in which the revolving cylinder is of hard- 
wood and part of the balls are lead composition and part lignum- 
vitse. 

Second. Dry mixing, in which the ingredients are blended by hand 
or b}' mechanical devices. In each of the above methods a small 
quantity of water is added. 



92 MILITARY EXPLOSIVES. 

Third. Wet mixing, in which the pulverized sulphur and charcoal 
are stirred into a saturated solution of saltpeter at a temperature of 
about 265° F. The mass is then spread on a floor to cool, after which 
it is ready for incorporation. The lumps formed in the cooling are 
easily broken. 

After mixing by either of the above methods, the material is spread 
. n the bed of the wheel mills in quantities of 300 pounds per wheel 
mill. The wheels, weighing 8 tons each, rotate on the material for 
3 hours at 10 rotations per minute. Edge runners keep the material 
worked toward the center of the tread of the wheels. Wheel cake 
or clinker formed during this operation is crushed or broken before 
pressing. 

In order to obtain uniform ballistic results, it is necessary that 
the powder be of uniform density before granulation. The horizon- 
tal hydraulic press has been found to be the best type for this opera- 
tion. The press plates, usually of aluminum, are so placed as to 
give press cake approximating three-fourths inch in thickness and 
about 24 inches square. The effective pressure on the press cake is 
estimated at 1,150 pounds per square inch. 

The press cake is cracked or granulated in the corning mill by feed- 
ing the cake between crusher rolls. Mechanically operated shaking 
screens separate the dust and coarse grains from the finished grain — 
the coarser lumps passing through successive crushing rolls — four 
sets of crushing rolls being the usual number per mill. This opera- 
tion is considered as the most hazardous of the various operations in 
the manufacture of black powder. Many devices have been employed 
to reduce the loss of property and life in the corning mill to a mini- 
mum. Most of these efforts have been toward conserving material 
that is lost, in the way of dust, and which during operation of the 
mill prevents the proper oversight of machinery or extraction of 
foreign substances in the powder ; and the use of labor-saving devices 
and mechanism so arranged that the mill can be operated from a 
place of safety. 

FINISHING. 

There are three accepted standard processes for finishing: 

First. In which drying and polishing are separate processes. 

Second. In which drying and polishing are one operation. 

Third. In which drying and polishing are one operation in a 
heated cylinder. 

The rounding or polishing of the grain is accomplished by tum- 
bling in a revolving wooden cylinder. The drying may be done in the 
same cylinder by forcing a current of warm air through the cylinder 
while the powder is being polished, or the powder may be removed 
from the cylinder and dried in stationary wooden trays. When 



MILITARY EXPLOSIVES. 



93 



heated cylinders are used the cylindrical surface of the revolving 
cylinder are steam jacketed, warm, dry air being forced through the 
cylinder as described above. The damage done by an explosion of a 
mill of this type leads to its abandonment. To glaze the polished 
grains a small quantity of pulverized graphite is added to the powder 
while the powder is hot from the tumbling or polishing process and 
the process continued for about half an hour. 

The drying and glazing process, when carried out on the single 
operation plan, requires 8 hours. 

PACKING. 

Before packing, the powder is rescreened and separated into grades 
according to specification requirements. Containers for black powder 
are made of soft steel and average about 9 inches in diameter bj' 
11 inches high, capacity 25 pounds, painted black, stenciled to show 
grades, lot number, maker, and contract number. 



INSPECTION. 

The various grades of black powder specified by the Ordnance De- 
partment are classified according to their percentage of composition, 
purity of material, size of granulation and rate of burning. For ex- 
ample, a certain latitude is permitted in the lower grades of black 
powder in the purity of the saltpeter and the percentage used in the fin- 
ished product. Similarly the use of those grades of charcoal which 
yield a larger percentage of dust is also permitted. With grade " C " 
black powder, however, where the uniform rate of burning is of 
utmost importance, the inspection details are governed by more rigid 
specifications. 

The different sizes of granulation form the basis for a secondary 
classification, as is indicated bv the following table : 



Powder. 


Screens. 


Passer. 


Toler- 
ances. 


Duster. 


Toler- 
ances. 


Army black powder: 
Grade A — 

No. 1 


Opening 


Inches. 

0.185 
4 tol 
.065 
.065 

10 tol 
.035 
.046 

14 to 1 
.025 
.0328 

20 to 1 
.0172 
.131 
6 tol 
.036 
.0041 
150 to 1 
. 0026 


Per cent. 
3 

3 

3 

3 

3 

3 


Inches. 

3.093 
8 to 1 
.032 
.046 

14 tol 
.025 
.0164 

35 to 1 
.0121 
.0164 

35 to 1 
.0122 
.046 

14 tol 
.025 


Per cent. 
5 




Mesh 






Diameter 




No. 3 


Opening 


5 




Mesh 






Diameter 




No. 4 


Opening 






Mesh 






Diameter 




Unglazed 


Opening 


5 




Mesh 






Diameter 




Grade B 


Opening 


5 




Mesh 






Diameter 




Grade C 


Opening 






Mesh. 


' 





















94 MILITARY EXPLOSIVES. 

Use. — The general uses of these powders are as follows: 



Designation . 



Uses. 



Army black powder: 
Grade A— 

No. 1 

No.3 

No. 4 

Unglazed 

Grade B 

Grade C 



All igniting charges. 

All primers, except as noted for powder No. 4; 3. 2-inch shrapnel head 

charges. 
Base charges for shrapnel; base charges for fuses; friction primers; 

model of 1914; obturation friction primer. 
Unglazed, pellets for primers and fuses. 
All saluting charges. 
Time train rings of fuses; pellets for delayed-action fuses. 



METHODS OF ANALYSIS. 

Sampling. — About 50 grams of the original sample are crushed in 
small portions in a porcelain mortar and passed through an 80-mesh 
sieve. ' All precautions are taken to avoid unnecessary exposure of 
the sample to the air during this treatment. If each portion is placed 
in a stoppered bottle as soon as sifted, there is no appreciable change 
in hygroscopic moisture content. The powdered sample is well 
mixed before its analysis is begun. 

Moisture. — About 2 to 3 grams of the powdered sample is spread 
in a thin layer on a tared 3-inch watch glass, carefully weighed and 
dried over sulphuric acid in a desiccator for three days or in a drying 
oven at a temperature of 60° to 70° C. to constant weight (about two 
hours). Cool in desiccator and weigh. Loss of weight is calculated 
as per cent moisture. 

Potassium nitrate. — In the determination of potassium nitrate by 
extraction with water about 10 grams of the finely ground sample are 
weighed in a Gooch crucible with asbestos mat and about 200 c. c. 
of water, in successive portions of 15 to 20 c. c. each, is drawn 
through the sample by means of suction. The complete solution of 
the nitrate is hastened by the use of warm or hot water, although 
200 c. c. of cold water is usually sufficient. The final portions of 
water passing through the crucible should be tested for soluble ni- 
trate by evaporation on a glass plate, or an excess of strong sulphuric 
acid containing a few crystals of diphenylamine may be added to a 
few drops of the water, and an intense blue coloration will indicate 
the presence of nitrate. 

The extraction is made on duplicate samples. After the complete 
removal of the nitrate the crucibles containing the portion insoluble 
in water are placed in a drying oven at a temperature of about 
70° and dried to constant weight, usually overnight, although five 
hours is generally sufficient. The percentage of loss of weight, minus 
the moisture content found as described above, represents the total 
water-soluble material, and includes, in addition to sodium or potas- 
sium nitrate, a small amount of water-soluble organic material from 



MILITARY EXPLOSIVES. 95 

the charcoal and the impurities in the original nitrate, such as chlo- 
rides and sulphate. As a check on this result an aliquot portion of 
the water extract may be evaporated to dryness on a steam bath, 
treated with a little nitric acid, again evaporated, heated to slight 
fusion, and weighed. 

Sulphur. — The dried and weighed material left from the extrac- 
tion with water consists of the sulphur and charcoal. The sulphur 
is determined by loss of weight on extraction with carbon disulphide 
in the Wiley extractor, or other suitable extraction apparatus, drying 
the insoluble residue to constant weight at about 100° C. 

Before drying this residue in a hot oven, the carbon disulphide 
should first be allowed to evaporate by placing the crucibles in a 
warm place away from any flame or other source of high temperature, 
as the vapors of carbon disulphide are very inflammable. 

The sulphur used in black powder should be brimstone," the flowers 
of sulphur not being suitable on account of the invariable presence 
of acidity. If flowers of sulphur are present, the extraction with 
carbon disulphide will be incomplete, due to the presence of insoluble 
amorphous sulphur. In this case it is necessary to resort to extrac- 
tion with hot aniline in order to remove all of the sulphur, pouring 
80 to 100 c. c. of aniline heated to 130-135° C. through the crucible 
in 10 c. c. portions, finally sucking dry, washing with a little alcohol 
to remove all of the aniline, drying and weighing. 

Charcoal. — The residue left from extraction of the sulphur is the 
charcoal, which is weighed direct as already noted. 

Ash. — The ash of the charcoal is determined by ignition of the 
insoluble residue over a Bunsen burner until all of the carbon has 
been burned off, and weighing. .The ash usually amounts to about 
0.5 to 1 per cent of the total powder. An unusually high value for ash 
may indicate incomplete extraction with water. 

Specific gravity. — Weigh 10 grams and transfer to a strong 50 c. c. 
specific gravity bottle with a perforated glass stopper. Fill the 
bottle one-half to two-thirds full with clean mercury. Place under 
vacuum and fill the remaining space with mercury. Weigh the 
bottle containing the powder and mercury at 19° to 21° C. The 
actual weight of the bottle plus mercury, plus powder, subtracted 
from the gross weight of bottle full of mercury, plus the powder 
taken at 19° to 21° C, represents the weight of mercury displaced. 
This weight divided by the specific gravity of mercury at 19° to 21° 
C. (13.59) gives the weight of an equal volume of water. The 
weight of the powder used, divided by this weight of water, repre- 
sents the specific gravity of the powder. 

Note. — To displace the air from the specific gravity bottle, attach a piece of 
heavy rubber tubing about 2 feet long to the bottle. Attach the other end of 
the rubber tubing to one leg of a Y tube. Extend the other leg of the tube by 



96 MILITARY EXPLOSIVES. 

means of a small piece of glass tubing and rubber tubing to dip into a vessel 
containing mercury. The stem of the Y is connected with the suction line. Close 
the rubber tube leading to the mercury vessel by means of a pinch cock. Turn 
on the suction and evacuate the specific gravity bottle, then close the suction 
line by means of a pinch cock placed close to the specific gravity bottle. Open 
the pinch cock on the tubing leading to the mercury vessel and nllow the mer- 
cury to flow into the specific gravity bottle. Repeat this operation until the 
bottle is filled with mercury. 

Determination of granulation. — Weigh out accurately 65 grams of 
the powder, empty it into the passer screen and shake vigorously over 
a sheet of brown paper for exactly one minute. Set aside the pow- 
der which has passed through the screen. Empty the material re- 
maining in the sieve onto the sheet of brown paper, striking the 
screen sharply with the fingers to remove any adhering powder 
grains. Again sift the material so obtained for exactly one minute, 
again empty the sieve, again removing any grains adhering to the 
mesh, and submit the material to a third sifting. Collect the mate- 
rial which has now failed to pass through the screen, weigh it to the 
nearest tenth of a gram, and calculate the percentage of powder 
which failed to pass through the passer screen. Empty onto the 
duster screen all the material which has been used in the passer- 
screen test, sift through three times as described above, collecting each 
time the material which passed through the screen, bring this mate- 
rial together, weigh it, and calculate the percentage of powder which 
passed through the duster screen. 

Moisture and ash free analysis. — Percentages on a moisture and ash 
free basis are calculated, by dividing the percentages of potassium 
nitrate, sulphur and carbon, respectively, by the remainder obtained 
by subtracting the sum of the percentages of moisture and ash from 
the sum total of the percentages obtained for potassium nitrate, sul- 
phur, carbon, moisture and ash. 

Determination of potassium. — Potassium may be determined by 
the perchlorate method. This method depends upon the fact that 
potassium perchlorate is practically insoluble in alcohol, whereas the 
perchlorates of the other bases which might be present are more or 
less readily dissolved by this solvent. The water solution contain- 
ing potassium salts must be free from sulphuric acid or sulphates; 
if it does contain them they can be removed by precipitation with 
BaCl 2 , and filtration. The solution is then evaporated to dryness 
and all acid fumes and ammonium salts driven off. The residue is 
dissolved in 50 c. c. of hot water containing considerably more than 
enough perchloric acid to combine with all the bases. Usually 5 to 
6 c. c. of perchloric acid solution of 1.12 specific gravity is sufficient. 
This solution is obtainable from chemical dealers. Evaporate the 
mixture until it is thick, add a little more hot water and 5 to 6 c. c. 



MILITARY EXPLOSIVES. 97 

more of the perchloric acid, and continue the evaporation, with stir- 
ring. Then heat the residue on a sand bath until dense white fumes 
are evolved. The cooled residue is then stirred with 20 c. c. of 97 
per cent alcohol containing 0.2 per cent by weight of perchloric acid, 
and transferred to a Gooch crucible, using 20 c. c. more of the same 
alcohol solution. The residue of potassium perchlorate in the Gooch 
crucible is then washed with about 20 c. c. of a mixture of equal 
volumes of ether and alcohol, dried at 120° to 130° C, and weighed. 
The barium perchlorate is readily soluble in the alcohol used, and 
magnesium does not interfere if the excess of perchlorate acid is 
large enough. Ammonium salts should be removed, as has been 
stated, because ammonium perchlorate is not readily soluble in 
alcohol. 

Chlorides, chlorates, and perchlorates. — Chlorides, chlorates, and 
perchlorates are identified as follows : Some of the solution in water 
is acidified with a few drops of nitric acid, an excess of silver nitrate 
added, the mixture heated to boiling, shaken well to coagulate the 
precipitate of silver chloride, and filtered. To the clear filtrate a 
few cubic centimeters of formaldehyde (40 per cent solution) is 
added and the mixture is then boiled. The formaldehyde reduces 
any chlorate present to chloride, which is precipitated as silver chlo- 
ride by the excess of silver nitrate present. The reaction is practi- 
cally complete if the mixture is allowed to stand on the steam bath 
for about an hour, although a considerably longer time is required 
for quantitative reduction. The precipitate is filtered off and the 
filtrate evaporated to dryness to remove excess of nitric acid, trans- 
ferred with a small volume of water to a crucible, enough dry sodium 
carbonate added to fill the crucible, the mixture dried carefully over 
a burner, and fused. The fused mass is dissolved in dilute nitric 
acid. If perchlorates are present, the solution will be found to con- 
tain a precipitate of silver chloride. 

BLACK-POWDER STORAGE. 

In the consideration of the storage of low explosives, of which 
black powder is an example, it must be remembered that these ma- 
terials are particularly sensitive to flame or spark. The restrictions, 
then, relative to the carrying of matches, to the cleanliness of the 
floors of magazines, to smoking, and to the use of nonsparking tools 
in general, should be rigidly enforced and carefully supervised. It 
is advisable also when working in the magazines where black powder 
is stored to wear rubber-soled shoes, the so-called " powder shoes." 
When it becomes necessary to open a box or container of black pow- 
der it should always be done with a wooden wedge and mallet, at 
132569—19 9 



98 MILITARY EXPLOSIVES. 

least 100 feet from the nearest magazine, and in a place which is pro- 
tected from rain or direct sunlight. No metal tools of any descrip- 
tion may be used. If it becomes necessary to repair a magazine, all 
explosives should be removed to a safe distance before work is 
started. 

Black powder should preferably be stored in a magazine con- 
structed of tile walls filled with sand. It should not be stored in 
the same building with dry picric acid, dynamite, or other high ex- 
plosive. The kegs may be placed in the magazine either on their 
ends or sides. 

In view of the fact that black powder has a tendency to absorb 
moisture, which causes deterioration and seriously affects the prop- 
erties of the powder, it is important that the storage magazines be 
dry and well ventilated. 



PART II — MILITARY HIGH EXPLOSIVES. 

INTRODUCTION. 

When the entire field of high explosives is considered, the term 
" military high explosive " has a restricted application to a relatively 
small number of substances. In determining the suitability of a 
high explosive for military use, careful consideration must be given 
to its various properties, including not only its strength but also its 
sensitiveness to shock or friction such as may occur in loading, its 
ability to withstand the shock of set-back in the gun, or, in 
the case of drop bomb explosives, ability to withstand penetration 
by bullets, its stability, hygroscopicity, action on metals, etc. 

These various requirements, together with questions of availability 
of raw materials, have excluded many high explosives which may be 
used successfully for commercial purposes. 

In the case of some of the explosives discussed herein, details of 
manufacture are not described, as such data is regarded by the 
manufacturers as confidential. 

99 



CHAPTER VII. 

TRINITROTOLUENE (T. N. T.). 

GENERAL. 

The importance of this explosive is based, first, upon its relative 
safety in manufacture, loading, transportation, and storage; second, 
on the fact that it is not hygroscopic ; third, on the lack of any tend- 
ency to form unstabled compounds with metals, and finally upon 
its powerful, brisant, explosive properties. 

Although trinitrotoluene was known as early as 1863, it was first 
suggested as an explosive only about 1890, but its importance from 
a military standpoint dates only from 1904. Since this time it has 
appeared as the principal constituent of many explosives and has 
been used by itself under such various names as triton, trotyl, tolite, 
trilite, trinol, tritolo, etc. It is commonly known in this country by 
the abbreviation T. N". T. The term trinitrotoluol, which is more 
generally used than trinitrotoluene, is less correct from the chemical 
point of view than the latter. 

PROPERTIES. 

T. N. T. usually resembles in appearance powdered maple or brown 
sugar, although in different grades of refinement or purity its color 
and appearance vary. When pure it is a crystalline powder of light 
yellow color. It dissolves readily in ether, acetone, alcohol, and 
various other solvents, but it is practically insoluble in water. 

Depending upon its purity, T. N. T. is classified by Ordnance De- 
partment specifications into three grades, designated as follows: 
Grade I, with a solidification point of at least 80.5° C. 
Grade II, with a solidification point of at least 79.5° C. 
Grade III, with a solidification point of at least 76° C. 
Grade III is obtained directly by the nitrating process as de- 
scribed below, while Grades I and II must be prepared by recrystal- 
lization or special chemical treatment of Grade III material. 

All grades of T. N. T. are poisonous under certain conditions and 
it is necessary that proper precaution be taken by those engaged in 
its manufacture or handling to avoid inhaling the vapors or dust 
from the hot or crystalline material. Good ventilation in manu- 
facturing or shell-loading plants is highly essential, and personal 
100 



MILITARY EXPLOSIVES. 101 

cleanliness should be enforced upon the workmen. All clothing 
should be changed upon the beginning and completion of work. 

T. N. T. is one of the most stable of high explosives, and when 
properly purified may be stored over long periods of time without 
alteration. It is quite insensitive to blows or friction but can be 
detonated by severe impact between metal surfaces. When ignited 
by flame it burns rapidly without explosion. Rapid heating of large 
quantities, especially in closed vessels, may, however, cause violent 
detonation. It should, therefore, be melted only in water or in 
steam jacketed melting kettles and never subjected to such tempera- 
tures as may result from the use of a free flame. 

T. N. T. has an important advantage over picric acid in the fact 
that it has no tendency to form compounds to react with metals, 
thereby producing sensitive salts. It will, however, react with 
alkalies, such as sodium hydroxide or sodium carbonate, to form 
unstable sodium salts which are quite sensitive. For this reason 
the use of alkalies in the purification of T. N. T. is not permissible. 

T. N. T. in crystalline form detonates readily under the influence 
of a No. 6 detonator (containing 1 gram of mercury fulminate). 
When compressed to a high density it requires a No. 8 detonator 
(containing 2 grams of mercury fulminate) , and when cast it is neces- 
sary to employ a booster charge of crystalline T. N. T., tetryl, or other 
more sensitive explosive, to insure complete detonation. 

The decomposition of T. N. T. on explosion may be regarded as 
occurring according to one of the following reactions, or more likely 
to a combination of both : 



or 



2 C H 2 (CH 3 ) (N0 2 ) 3 =12 C0+2CH 4 +H 2 +3N £ 
2 C 6 H 2 (CH 3 )(N0 2 ) 3 =12 C0+5H 2 +3N 2 +2C 



The deficiency in oxygen as indicated by both of these reactions is 
always apparent from the black smoke produced by the explosion of 
T. N. T. This deficiency of oxygen may be compensated for by the 
addition of such substances as ammonium nitrate or sodium nitrate 
in various proportions, the resulting mixtures being designated as 
amatol and sodatol, respectively. 

Like nitroglycerine dynamite, T. N. T. may be classed as a " quick 
acting " explosive. It detonates at a rate varying from about 17,000 
feet per second for loosely compressed material to nearly 25,000 feet 
per second for material cast or compressed to its maximum density. 
Forty per cent dynamite has a rate of detonation of about 15,000 feet 
per second. Various other tests such as the ballistic pendulum test 
and the Trauzl lead block test show T. N. T. to be, in general, some- 
what stronger and quicker in action than 40 per cent dynamite. 



102 MILITARY EXPLOSIVES. 

MAN UFACTURE. 

The manufacture of T. N. T. involves the following processes: 

First. Nitration of toluol to mononitrotoluol. 

Second. The further nitration of the mononitrotoluol to the di- 
nitro and finally to the trinitrotoluol. 

Third. Washing the finished product until free of acid. 

Fourth. Purification by remelting and chemical treatment or re- 
crystallization. 

Fifth. Granulation, screening, and drying. 

The process of nitration of the pure toluol with a mixture of nitric 
and sulphuric acids may be carried out in various ways, for example : 

(1) The one-stage process, where a large excess of a strong mixed 
acid is used and the temperature gradually raised, with the result 
that trinitrotoluol is produced in the one process without transfer 
or separation of spent acid from intermediate products. 

(2) The three-stage process, where, by the use of three different 
acid mixtures and different conditions of temperature, etc., there are 
successively produced mono-, di-, and trinitrotoluol, each stage being 
carried out in a different nitrator. 

(3) The two-stage process, where either mono- or dinitrotoluol 
is produced in the first stage and trinitrotoluol in the second. 

The nitrator used for the single-stage process consists of a cast- 
iron or steel cylindrical tank having a capacity of about 1,000 gallons, 
equipped with a steam jacket and cooling coils. The agitation in the 
kettle is effected by means of baffles fastened to the side of the tank 
operating against a mechanically driven propeller. The mixed 
acid used consists of approximately 76 per cent H 2 S0 4 and 23 per 
cent HN0 3 . After the acid has been blown into the nitrator its 
temperature is reduced to 30° C. and the charge of toluol slowly run 
in by gravity. It takes about one hour and a half for the complete 
addition of the toluol, during which time care is observed to keep 
the temperature between 30° and 50° C. Finally the steam is turned 
on and the temperature gradually raised over a period of several 
hours until a maximum of 110° C. is reached, at which temperature 
the charge is "cooked" for about three hours. A sample is then 
taken and a determination made of the solidification point. If this 
is below T 70° it is necessary to cool the charge and add an additional 
amount of mixed acid. This procedure is continued until the test 
shows that the conversion of the dinitro to the trinitro has been 
completed. 

In the two and three stage processes of nitration a different pro- 
cedure is carried out and the nitration of the toluol to the mono-oil 
is effected by utilizing the spent acid recovered from a previous 
nitration. In fact, the nitration process consists on the one hand of 



MILITARY EXPLOSIVES. 103 

the progressive nitration of the material, and on the other of the 
progressive denization of the acid by utilizing the spent acid from 
the next higher nitration. In other words, the strongest acid is used 
for the third nitration. This strong acid consists of a mixture of 
fnming sulphuric acid and strong nitric acid. 

The process is very similar to that employed for the one-stage 
process with the exception of the method of addition and separation 
of the acids. The mononitration is first accomplished by running 
into the nitrator a charge of spent acid from previous dinitration 
fortified to the proper HNO s content. The toluol is then added in 
approximately the same proportion, with continual stirring. This 
first nitration period is usually about 1 hour and 20 minutes and the 
temperature is maintained below 150° F. At the end of the operation 
the mixture of spent acid and mononitrotoluol is allowed to stand 
until the two constituents have separated enough so that the acid may 
be drawn off. The mono oil is then blown over to another nitrator, 
where it is subjected to a second nitration similar to the one just 
completed, except that in this case the spent acid is that from the 
trinitration, properly fortified to the required HNO ;! content. The 
dinitrotoluol resulting from this process is usually given the third 
nitration in the same nitrator, using a strong mixed acid as already 
noted. The separation of the finished product from the spent acid is 
effected by gravity, the spent acid being adjusted for use in the next 
lower nitration as above indicated. 

The residue of mother liquors obtained from the di- and trini- 
trotoluols possesses the property of colloiding with pyro cotton in a 
manner somewhat similar to that of nitroglycerine, and this prop- 
erty is made use of by certain manufacturers for the manufacture of 
certain classes of sporting powders. 

Humphrey (Jour. Ind. Engng. Chem., v. 8, November, 1916) 
states that, contrary to the usual belief, the yield of T. N. T. from the 
di or second nitration, at a given temperature, is not the function of 
the water content of the mixture (except that too strong an acid 
tends to oxidize the material and in this manner lowers the per- 
centage of yield), but is rather dependent upon the proper low tem- 
perature during nitration. The mono nitration yields a product 
containing a mixture of about 4 per cent of the meta nitrotoluol in 
addition to the, ortho and para isomers. The subsequent nitration 
changes the meta mononitrotoluol into the beta and gamma trinitro- 
toluenes, which differ from the alpha form in chemical properties and 
are regarded as impurities. Depending upon the completeness with 
which the last nitration is peformed there may be either a large 
amount of dinitrotoluene present if improperly carried out, or, if 
correctly done, a relatively small amount. 



104 MILITARY EXPLOSIVES. 

In addition to these impurities, there may also be such bodies as 
tetranitromethane which possesses the undesirable property of lower- 
ing the settling point of the pure alpha T. N. T. If the nitration 
has been properly carried to completion, there should not be present 
more than 4 per cent beta and gamma T. N. T. This condition is 
not usually attained under manufacturing conditions and it is, there- 
fore, necessary to recrystallize and repurify the T. N. T. in order 
that the impurities may be eliminated, and a product of the required 
setting point for Grade I, T. N. T. (80.5° C), obtained. 

PURIFICATION. 

The crude trinitrotoluene, which, due to the heat of reaction, is in 
the form of an oil, is run from the nitrator into neutralizing tubs 
which have the shape of a cone at the bottom. At the apex of the 
cone a gateway valve for regular discharge from the tub is provided. 
Steam coils for heating and air coils for agitation are both provided. 
Wash water is drawn off by means of suction through a suitable pipe 
which reaches the tub near the top and extends along the side wall 
to about 2 feet from the bottom. A small quantity of sodium sul- 
phite can be used to assist in the purification at this point, although 
it is not necessary to do so. Washing is carried on until no test for 
acidity is shown by the use of litmus paper. The neutral T. N. T., in 
the form of oil, is now pelleted by running into cold water, for trans- 
portation to the graining house, or can be transported in the molten 
condition to suitable storage tanks through heated pipe lines. If 
pelleted, these pellets are transported to storage tanks, as above men- 
tioned, and again melted before running into the crystallizing kettles. 
The storage tanks are kept at an approximate temperature of 95° C., 
and are provided with a gateway screw valve from which the molten 
charge is drawn off into the graining kettles. These kettles are made 
of cast iron, in one piece, and the junction of the bottom and the side 
Avails is rounded so that plows can scrape the T. N. T. loose from the 
sides. The lower part of the kettle is fitted with a jacket into which 
steam or cold water may be discharged. As the plows are started, 
the charge cools down and the crystals begin to form on the sides 
which increase until the whole mass becomes plastic. During the 
operation all moisture is driven off and the T. N. T. produced is in a 
fine crystalline condition. The T. X. T. produced is usually better 
than Grade III, which is 76° melting point. If it is desirable to 
obtain T. N. T. of Grades I and II, recrystallization from either alco- 
hol or sulphuric acid or a treatment with sodium sulphite must be 
made. A brief description of each is given below. 

Crystallization from sulphuric acid. — The fine crystals produced 
in the graining kettles are dissolved in hot sulphuric acid, usually 



MILITARY EXPLOSIVES. 105 

weight for weight, and cooled. The purified crystals thus settling 
out are washed free from acid and regrained to such a degree of fine- 
ness as to pass Ordnance Department specifications. The crude ma- 
terial held in sulphuric acid is accumulated until such time as the 
amount .warrants separate purification. 

Crystallisation from alcohol. — The fine crystals of T. N. T. are dis- 
solved in warm 95° alcohol denatured with benzene. This alcoholic 
solution is filtered and cooled, and sufficient alcohol is distilled off 
to cause T. N. T. of setting point of not less than 80.5° to separate 
out. This distillate is recovered and used over again. The crude 
T. N. T., commonly known as " still residues," is usually used up in 
the manufacture of commercial explosives. 

Sulphite purification. — The sodium sulphite treatment is usually 
applied by taking the fine crystals from the graining kettles, placing 
them in bins or cars which are equipped with a Filtros bottom. 
These bins or cars are given one hot water washing, then four wash- 
ings with the 5 per cent solution of sodium sulphite, then one warm 
water washing followed by sufficient cold water washings to remove 
the last traces of the red color which is formed in the treatment. 
The purified crystals thus obtained can be dried, sieved, and packed, 
or regrained, as may be necessary to meet specifications. 

USE. 

Grade I T. N. T. is considered more expensive than Grades II 
and III, because it requires additional purification; it is therefore 
used only in boosters for high-explosive shell, where the best grade 
of material is required. Grade II is used as the bursting charge for 
high-explosive shell, either alohe or mixed with an equal weight 
of ammonium nitrate to form 50/50 amatol (the T. N. T. in either 
case being melted so that the shell is filled by a casting or pouring 
process). Grade III is used only in 80/20 amatol, where it is mixed 
in the molten state with four times its weight of ammonium nitrate 
and filled into high-explosive shell by hand stemming or by means 
of a screw filling machine. 

A charge of about If pounds of cast T. N. T. in a 75-mm. high- 
explosive shell weighing about 9^ pounds breaks up the shell into 
approximately 700 fragments. 

Other military uses for T. N. T. are as a bursting charge for hand 
grenades, rifle grenades, aeroplane drop bombs, naval submarine 
mines, and depth bombs. In aeroplane bombs it has the disadvantage 
that penetration of the bomb by a rifle bullet may cause an explo- 
sion of the charge. This is also true of amatol, which has been used 
more extensively than T. N. T. in drop bombs. When used in gren- 
ades, the crystalline Grade II, T. N. T., is loaded by means of vi- 



106 MILITARY EXPLOSIVES. 

brators which "jolt" the grenades until they are completely full. 
Grade III is suitable for mines or drop bombs and is loaded by cast- 
ing, as in the case of high-explosive shell. 

T. N. T. is also used for military purposes in demolition work on 
bridges, railroads, etc., and for land mines placed under enemy 
trenches or fortifications. For demolition work carried on by the 
Engineer Corps the T. N. T. is made up in the form of small, highly 
compressed blocks which are graphited on their surfaces and then 
copper plated; this protects them from crumbling in handling and 
renders them waterproof. 

T. N. T. has been demonstrated to be suitable for all kinds of 
blasting work where 40 per cent dynamite is used, and to give prac- 
tically equal effects. It is well adapted for "adobe" shooting or 
"mud capping," terms applied to the breaking up of large rocks or 
bowlders by means of a charge of high explosive placed on the rock 
and confined only by means of a shovelful of mud or wet earth 
thrown over it. Only quick-acting explosives can be successfully 
used for such work. Even in drill holes containing water, T. N. T. 
gives excellent results because of the fact that it is insoluble in 
water. Its use for blasting has, however, been negligible because of 
the fact that military requirements have made it unavailable and ex- 
pensive as compared with commercial dynamites. 

On account of its ability to act as a "booster" in bringing about 
the detonation of more insensitive explosives, T. N. T. has been em- 
ployed as a partial substitute for the mercury fulminate in commer- 
cial electric blasting caps or detonators. A charge of T. N. T. is 
pressed into the bottom of the cap, covered by a small priming charge 
of fulminate and the whole charge confined by a perforated copper 
capsule pressed on top of the priming charge. Such T. N. T. det- 
onators have been extensively used abroad but have not met with 
great success in this country. 

" Cordeau Bickford," a trade designation for detonating fuze, con- 
sists of a flexible lead tube, smaller in diameter than a lead pencil, 
filled with T. N. T. It is quite extensively used in certain blasting 
operations, especially for insuring the complete detonation of large 
charges of dynamite. The detonating fuze being passed through 
the entire length of the charge, and detonated at its external end by 
means of an ordinary blasting cap, transmits its high rate of deto- 
nation to the entire charge of dynamite. 

INSPECTION. 

Specifications. — The chemical and physical requirements pre- 
scribed by Ordnance Department specifications for the different 
grades of T. N. T. are as follows : 



MILITARY EXPLOSIVES. 



107 



Solidification point — 

not less than. 

Ash — not more than 

Insoluble matter — not 

more than. 
Moisture — not more than. 
Aciditv — not more than 

(as H2SO4). 

Color 

Fineness 



Grade I. 



Grade II. 



80° C. 



0.1 percent.. 
0.15 per cent. 



79.5° C. 



0.1 percent.. 
0.15 per cent. 



0.1 percent 0.1 percent.. 

0.01 percent 0.01 percent. 



Light yellow 

30-mesh sieve, opening 

0.0183 inch, wire 0.015 

inch. 



Light yellow 

12-mesh sieye, opening 

0.058 inch, wire 0.025 

inch. 



Grade III. 



76° C. 

0.1 percent. 
0.15 percent. 

0.1 percent. 
0.01 percent. 



12-mesh sieve, opening 
0.058 inch, wire 0.025 
inch (or flake). 



It will be noted that the three grades vary only in solidification 
point and fineness. 

ANALYSIS AND TESTING. 

The most important test in connection with the inspection of T. N. 
T. is the determination of its solidification point or " setting point." 
This temperature serves as an indication of the purity of the explo- 
sive, inasmuch as the presence of moisture, lower nitrating products, 
objectionable amounts of isomers, and other impurities all tend to 
lower the solidification point. In order, however, to insure the proper 
degree of purity, additional determinations of ash, insoluble mattei, 
moisture, and acidity, are required by Ordnance Department specifi- 
cations. The prescribed methods of conducting these tests are as fol- 
lows : 

Solidification point : The apparatus used consists of the following 
parts: A test tube 1 inch in diameter and 6 inches long is fitted 
through a cork into a second test tube 1| inches in diameter and 7 
inches long, which in turn is set into a large-mouth liter bottle. Into 
the inner tube is fitted a cork stopper through which are three open- 
ings. One is in the center for the standard thermometer, which 
should be graduated in 1/10° C. One is immediately at the side of 
the center hole and is for a small thermometer which is passed just 
through the stopper and which reading is taken as the average tem- 
perature of the exposed stem of the standard thermometer in making 
the stem correction. The third hole in the stopper is a small V-shaped 
opening at the side, through which passes a wire whose lower end is 
bent in a loop at right angles to the axis of the tube and which is 
used as a stirrer. 

The test is carried out as follows: Place a 50-gram sample of 
T. N. T. in the inner tube and melt it in an oven, the inner tube being 
separated from the rest of the apparatus for this purpose. When 
the temperature has reached about 90° C. the tube is replaced in 
the apparatus, the standard thermometer placed so that the bulb is 
approximately in the center of the molten T. N. T., and the small 
side thermometer put in place. The stirrer should already be in 



108 MILITARY EXPLOSIVES. 

the molten T. N. T. Stirring is continued vigorously as the tempera- 
ture falls, and the thermometer must be watched very carefully. 
When a point is reached where the temperature -begins to rise, 
owing to the heat of crystallization, readings should be recorded 
about every 15 seconds until the maximum temperature is noted. 
This temperature usually remains constant for several minutes until 
crystallization is complete, and observation should be continued until 
it is certain that the maximum temperature has been reached. This 
takes from 5 to 10 minutes after the beginning of crystallization. 
This maximum temperature with the correction for emergent thread 
is taken as the solidification point of the sample. 

Ash : Burn a known weight, approximately 5 grams, moistened 
with sulphuric acid, in a tared crucible. To compensate for reduc- 
tion of any metallic salts, add a few drops of nitric acid and sul- 
phuric acid and again ignite and weigh. 

Insoluble matter: Boil a known weight, approximately 10 grains, 
with 150 c. c. of 95 per cent alcohol. Filter while hot through a 
tared Gooch and wash with hot alcohol. Dry to constant weight at 
100° C, cool and weigh. 

Moisture : A known weight, approximately 5 grains, is exposed in 
a desiccator over sulphuric acid in a watch glass to constant weight. 

Acidity : A known weight, approximately 10 grams of the sample, 
is melted and shaken with 100 c. c. of neutral boiling water and 
allowed to cool. The sample is then remelted and again extracted 
with 50 c. c. of neutral boiling water. The total water extract is 
cooled and titrated with N/10 sodium hydroxide, using phenolphtha- 
lein as an indicator. Calculate results as per cent sulphuric acid in 
the original sample. 

Nitrogen : The determination of nitrogen is not required as a part 
of routine inspection and is only made in particular cases ; e. g., where 
the solidification point is found to be unusually low. There are 
various modifications of the Kjeldahl method which give fairly ac- 
curate results with T. N. T. ; e. g., the method described in Bureau 
of Mines Technical Paper No. 160. For accurate determinations, 
however, the Dumas combustion method is considered far more re- 
liable if properly conducted. 

Fineness: It is required that Grade I, T. N. T., should pass com- 
pletely through a screen containing 30 mesh to the linear inch, the 
openings being 0.0138 inch and the wire 0.015 inch in diameter. 
Grades II and III are required to pass a 12-mesh screen having 
openings 0.058 inch and wire 0.025 inch. 

STORAGE. 

The type of magazine best designed for the storage of T. N. T. is 
similar to that used for ammonium picrate and wet picric acid. The 



MILITARY EXPLOSIVES. 109 

buildings should not be larger than 26 by 42 feet and may be con- 
structed of tile, asbestos protected metal, or tile walls filled with sand. 

The cleanliness both within and without the magazine should be 
carefully watched and the same rules applied as in the case of the 
storage of smokeless powder. Special regulations, however, for this 
material are not necessary, as is the case, for instance, with black 
powder or picric acid. The loading of shells, by casting or by tamp- 
ing, should be performed when necessary, as far from the magazine 
as is possible, and in no case less than 200 feet. 

The use of the automatic sprinkler system in the magazines in 
which T. N. T. is stored has been recommended as protection against 
incipient fires by the National Board of Underwriters, the action of 
the sprinklers tending to prevent overheating and the subsequent 
possible detonation of large quantities of high explosives. (See Sug- 
gested Protection for Munition Magazines, National Board of Under- 
writers, Committee on Fire Protection and Engineering Standards, 
76 William Street, New York City.) 

The poisonous effects already mentioned as resulting from the 
handling of T. N. T. both in the manufacture and storage must be 
well considered and every precaution observed to protect the work- 
men at all times. 



CHAPTER VIII. 
AMMONIUM PICRATE (EXPLOSIVE D). 

GENERAL. 

The use of ammonium picrate as an explosive was patented by 
Nobel in 1888 (Mosenthal, Jour. Soc. Chem. Ind., vol. 18, p. 447, 
May, 1899), although even prior to that time Brugere made use of 
a mixture of ammonium picrate and sodium nitrate as a propellant 
explosive. 

The importance of ammonium picrate as a military explosive is 
due entirely to its marked insensitiveness to shock and friction, which 
makes it well suited for use as a bursting charge in armor-piercing 
projectiles. From the standpoint of explosive strength, however, 
this explosive is inferior to T. N. T. 

PROPERTIES. 

Ammonium picrate is soluble in water, crystallizing from its 
solution in orange-yellow needles, darker in color than picric acid. 
It resembles picric acid in its bitter taste and property of dyeing 
the skin, clothing, etc, of those engaged in its manufacture or 
handling. 

It has a much greater tendency to absorb moisture than has picric 
acid, samples having been found to absorb over 5 per cent by weight 
of water during storage for one month in an atmosphere saturated 
with moisture. 

Like picric acid, ammonium picrate can react with metals to form 
metallic picrates, but it reacts with much less readiness than picric 
acid; in fact, when dry its action is almost negligible. Wet am- 
monium picrate reacts slowly, especially with copper or lead, to 
form picrates, which are particularly sensitive and dangerous. 

Ammonium picrate does not melt on heating, but explodes when 
heated to a temperature of about 300° C. Small traces of metallic 
picrates may, however, lower this ignition temperature appreciably. 

Ammonium picrate is the least sensitive of all military explosives 
used as the bursting charge for shell. Its insensitiveness to shock 
accounts for it being given preference over T. N. T. or amatol as 
the bursting charge for armor-piercing, base-fuzed shell. It is also 
more insensitive to detonation by means of mercury fulminate than 
is T. N. T. Impact tests, made by dropping a weight on a small 
sample of the explosive spread between metal surfaces, show no very 

110 



MILITARY EXPLOSIVES. Ill 

great difference in the sensitiveness of T. N. T. and ammonium 
picrate, but more reliable conclusions can be obtained by the results 
of actual firing of loaded shell against armor plate, Avhereby am- 
monium picrate is readily shown to be the least sensitive. 

Ammonium picrate is slightly less powerful than T. N. T. The 
Trauzl test shows an expansion of approximately 240 c. c. from the 
former as compared with about 260 c. c. for T. N. T. This difference 
is, however, due to the fact that T. N. T. as used has a higher 
density than can be readily obtained with ammonium picrate. As a 
charge for high-explosive shell, T. N. T. is required to have a density 
of at least 1.55, while the specified density of ammonium picrate is 
1.33 to 1.37. At equal densities ammonium picrate is slightly more 
powerful than T. N. T. At a pressure of about 12,000 pounds per 
square inch the two explosives have the same densities. 

Like T. N. T. and picric acid, ammonium picrate liberates free 
carbon on explosion, giving a black smoke. These products of ex- 
plosion, although more disagreeable in odor, are less poisonous than 
those from T. N. T. and picric acid, in that they contain less carbon 
monoxide. 

MANUFACTURE. 

The manufacture of ammonium picrate consists in the main of a 
simple neutralization of picric acid by means of ammonia either 
alone or in combination with ammonium carbonate. This process is 
not attended with any serious manufacturing difficulties or dangers, 
provided one excludes the possibility of leaking ammonia pipes. 
The details of manufacture are as follows : 

Approximately 300 pounds of picric acid are mixed in 500 gallons 
of water at room temperature and then slowly heated by direct steam. 
As the mixture warms, aqua ammonia is added at the bottom of the 
tank until neutralization is completed. In some factories it is the 
practice to add a faint excess, thus insuring complete neutralization 
of all the picric acid, this condition being evidenced by the forma- 
tion of a reddish colored crystalline mass of ammonium picrate. 
When this stage has been reached the resulting material is dropped 
into tanks for crystallization. These tanks are so equipped that a 
continual agitation of their contents can be maintained by air with 
the object of accelerating the crystallizing of the ammonium picrate 
during the cooling. When the mass has cooled to about 25° C. 
the crystals are separated from the mother liquor by filtering or 
draining. From the crj^stallizing tank the ammonium picrate is 
taken to the dry house where it is subjected to a temperature of 
about 45° C. for eight hours in drying bins which are so constructed 
that warm air circulates constantly through the mass. Finally the 
dried material is screened by means of a rotating barrel screen and 



112 MILITARY EXPLOSIVES. 

sent directly to the packing room. The finished product is then 
packed in 50-pound boxes lined with waterproof paper and sent 
to storage. 

REWORKING AMMONIUM PICRATE. 

This operation consists in redissolving impure or waste ammonium 
picrate in water, removing the impurities by filtration, then heating 
the solution by steam coils until it has been evaporated sufficiently to 
produce crystallization. From here on the reworking operations 
are exactly the same as those followed out in the manufacture of the 
new material. The reworking of ammonium picrate is made neces- 
sary on account of the fact that when this material has once been 
subjected to heavy pressure, as is always the case in shell-loading 
operations, it is much more sensitive to detonation than new material. 
In this condition it is unsafe to load, inasmuch as continued repress- 
ing may result in detonation. 

USE. 

As has been mentioned, ammonium picrate is used as the bursting 
charge for armor-piercing shell on account of its superior insensi- 
tiveness to shock, which permits the shell to pass through the armor 
before exploding. Owing to the fact that it can not be melted without 
decomposing it must be loaded into the shell by hydraulic pressure or 
hand stemming. The interior of the shell is covered with a suitable 
nonmetallic paint or varnish and a moisture-proof seal provided 
around the booster at the base of the charge by means of cast T. N. T. 

Ammonium picrate has also been used to some extent in France, 
mixed with potassium nitrate, as a propellant explosive for use in 
guns. 

It has no commercial use as an explosive, although it enters into the 
composition of numerous patented blasting explosives which have not 
been used to any great extent. 

INSPECTION. 

Specifications. — Ordnance Department specifications prescribe the 
following chemical requirements for ammonium picrate: 
It must not contain — 

(a) Less than 5.60 per cent ammoniacal nitrogen. 

(b) More than 0.20 per cent moisture. 

(c) More than 0.10 per cent sulphuric acid (free and combined). 

(d) More than traces of nitrates. 

(e) More than 0.20 per cent insoluble material. 
(/) More than 0.20 per cent mineral matter (ash). 
(g) Free ammonia. 

(h) More than 0.5 per cent nitro phenols. 



MILITARY EXPLOSIVES. ] 13 

ANALYSIS AND TESTING. 

The following tests and determinations are made on ammonium 
picrate to determine its suitability for military use : 

Moisture: Dry a known weight, approximately 10 grams, thinly 
spread in a tared glass dish at 95° C. for two hours or to constant 
weight. 

Insoluble material: Dissolve a known weight, approximately 10 
grams, in 150 c. c. of hot distilled water, and boil for 10 minutes. 
Filter on a tared Gooch, wash thoroughly with hot distilled water 
and dry to constant weight at 100° C. 

Ash: Satur&te a known weight, approximately 1 gram, with 
melted paraffin and burn off carefully. Ignite the residue, cool and 
weigh. 

Nitrophenols : A known weight, approximately 10 grams, of a 
finely ground sample is placed in a small beaker with 50 c. c. of 
chloroform and allowed to stand 30 minutes at room temperature 
with frequent stirring. Filter into a 100 c. c. tared flask, washing 
the residue with 25 c. c. of chloroform. Evaporate the filtrate to 
dryness on a steam bath and weigh residue. Dissolve the residue 
in distilled water and ammoniate. Evaporate the solution to dry- 
ness on the steam bath. Extract the residue with 22 c. c. of chloro- 
form, filter and evaporate the chloroform filtrate to dryness in a 
tared dish and weigh. The difference in weight between the first 
chloroform extract residue and the second chloroform extract residue 
equals picric acid. 

Ammoniacal nitrogen : A 1-gram sample of the ammonium picrate 
to be analyzed is placed in a 400 to 500 c. c. Kjeldahl flask. The flask 
is equipped with a two-hole rubber stopper which carries an exit 
tube, leading away to a bottle containing N/10 sulphuric acid, and an 
ingress tube, reaching to its bottom, through which air (that has al- 
ready been dried and freed from ammonia by passage through con- 
centrated sulphuric acid) may be bubbled; 20 c. c. of water are in- 
troduced into the flask, 12 c. c. of 5 per cent sodium carbonate solu- 
tion are added, the flask is set in a boiling water bath and ammonia 
free air is bubbled through until the contents of the flask have been 
evaporated to dryness. The ammonia is absorbed by bubbling the 
air through 50 c. c. of N/10 sulphuric acid, a bulb full of very small 
holes, such as may conveniently be made with a hot platinum wire, 
being used for the purpose. To deal with the possibility of splashing 
of the sulphuric acid, the exit tube from the bottle is equipped with 
a trap. The excess sulphuric acid is titrated with N/10 sodium 
hydroxide, using methyl red or sodium alizarine sulphonate as an 
indicator, the amount which has been consumed is noted, and the 
ammoniacal nitrogen of the sample is calculated. 
132569—19 10 



114 MILITARY EXPLOSIVES. 

Sulphuric acid : Dissolve a known weight, approximately 5 grains, 
in 100 c. c. of hot distilled water, filter and wash with 25 c. c. of hot 
distilled water. Acidulate with hydrochloric acid - and heat, then 
add a hot solution of barium chloride with constant stirring, allow 
to settle and filter on a tared Gooch while hot ; thoroughly wash with 
hot distilled water and dry to constant weight at 100° C. Calculate 
results as sulphuric acid in original sample. 

Nitrates : Determine by testing a water solution of the sample with 
diphenylamine and concentrated sulphuric acid. 

Free ammonia: Presence determined by titrating water solution 
with N/10 sulphuric acid, using methyl orange or sodium alizarine 
sulphonate as an indicator. 

STORAGE. 

The storage of ammonium picrate is governed by the same rules 
as are applicable for the storage of T. N. T., both as to type of maga- 
zine and rules for handling, and special regulations governing this 
particular explosive are not necessary. It is to be noted, however, 
that ammonium picrate which has been repressed at a shell-loading 
plant and removed from a shell is very much more sensitive to shock 
or blow than new material, and there are cases on record where 
serious accidents have happened in the loading of shells with ammo- 
nium picrate so treated. If it becomes necessary then to store this 
material, special precautions should be observed to protect it against 
a shock, or fire, and it preferably should be stored in a building by 
itself. 

Although less sensitive than T. N. T. ammonium picrate can be ex- 
ploded by severe shock or friction, is highly inflammable, and when 
heated to a high temperature may detonate. It is therefore necessary 
that it be treated with proper care as a high explosive. 

Since it absorbs moisture it should be stored in dry magazines and 
protected from dampness. Moisture, however, has no effect on 
ammonium picrate except to reduce its explosive strength and its 
sensitiveness to detonation. 

Ammonium picrate is always stored in wooden containers because 
of the possibility of its forming sensitive metallic picrates in contact 
with metals, especialty when moist. 



CHAPTER IX. 
PICRIC ACID. 

GENERAL. 

Picric acid or trinitrophenol was first adopted as a military high 
explosive by the French Government in 1886, under the name of 
melinite, and has since been used to a greater or less extent by almost 
all countries, with or without the addition of various materials in- 
tended to reduce its melting point or increase its strength. The Brit- 
ish explosive designated as Lyddite, and the Japanese explosive 
Schimose, are both cast picric acid, and various names are given to 
other shell explosives, the chief component of which is picric acid. 

The fact that picric acid readily forms dangerous] y sensitive salts 
with metals has practically precluded any extensive use of it as an 
explosive in this country, its present interest to the United States 
Government being that it is the raw material used in the manufacture 
of ammonium picrate. 

PROPERTIES. 

Picric acid is a lemon-yellow crystalline solid, only slightly solu- 
ble in water but soluble in alcohol, benzene, and other organic solvents. 
A very small amount is, however, sufficient to color a large volume 
of water a distinct yellow color. It likewise stains the skin of 
workmen, colors clothing, hair, and everything else with which it 
comes in contact, and has an exceedingly persistent, disagreeable, 
bitter taste. Its property of coloring is utilized in the dye industry, 
and, in fact, picric acid was long known as a dyestuff before its ex- 
plosive nature was discovered. It has no tendency to absorb mois- 
ture from the air. 

Picric acid melts at a temperature of about 122° C. when pure, and 
is usually required for explosive use to have a melting (or solidify- 
ing) point of at least 120° C. (248° F.). 

Being an acid, it has the property of combining with ammonia 
and alkalies and with many of the metals, forming salts which are 
called picrates. Most of the picrates are much more dangerous than 
picric acid itself, and it is therefore necessary that metals be kept 
from direct contact w T ith picric acid by means of suitable varnishes 
or lacquers. Tin is the only common metal which is not attacked 
by picric acid. Lead reacts so readily to form highly sensitive lead 

115 



116 MILITARY EXPLOSIVES. 

picrate, that it is necessary to entirely eliminate lead apparatus, pipe, 
etc., in the manufacture of picric acid and even in the manufacture 
of the nitric acid used in making picric acid. 

Picric acid is a weak poison, the chief danger in connection with 
its use being probably the fumes given off from the molten ex- 
plosive used in shell loading. Practically no trouble from poisoning 
results in the manufacture or handling of picric acid ; care must be 
taken, however, to avoid the breathing of the large amounts of picric 
acid dust that may arise in screening or packing dry picric acid. 

Picric acid is entirely stable if kept from contact with materials 
with which it can combine, such as alkalies or metals. It has no 
tendency to decompose at any temperatures which it might meet in 
storage. On sudden heating at temperatures much above its melt- 
ing point (122° C), it may explode, although many cases are noted 
where considerable quantities of picric acid have burned without ex- 
plosion. The presence of any trace of explosive that will detonate 
more readily, such as metallic picrates, may cause the sudden de- 
tonation of burning picric acid. 

It is somewhat more sensitive to shock or friction than T. N. T., 
and more readily detonated by means of a detonator. For such 
reasons, transportation regulations require that for bulk shipment 
picric acid must contain at least 10 per cent of water, because in this 
condition it is regarded as an inflammable only. Wet picric acid is, 
of course, thoroughly dried before use for explosive purposes. 

Picric acid is one of the most powerful of military explosives. Its 
high strength or concussive effect is due to its high rate of detona- 
tion, which, for the cast or highly compressed explosive, is about 
25,000 feet per second — slightly greater than that of T. N. T. under 
the most favorable conditions. By both the Trauzl lead block test 
and the ballistic pendulum test, picric acid shows appreciably greater 
strength than T. N. T., being exceeded only by tetryl and T. N. A. 
The results of these methods of testing are confirmed by actual frag- 
mentation tests of high explosive shell, where it is found that a 
larger number of shell fragments is produced from picric acid than 
from T. N. T. at equal loading densities. 

MANUFACTURE. 

The raw material from which picric acid is derived is benzene 
(often called benzol). This substance must not be confused with 
benzine, which is essentially gasoline, obtained by the distillation of 
petroleum. Benzene is an inflammable liquid obtained as a by- 
product in the manufacture of coke by recovery from illuminating 
gas or by "cracking" oils at high temperatures. 



MILITARY EXPLOSIVES. 117 

Picric acid may be manufactured from benzene by three distinct 
processes, designated respectively as the phenol process, the chlor- 
benzol process and the catalytic process. 

Phenol process. — Practically all of the picric acid produced in this 
country during the war was made from phenol (carbolic acid). 
Phenol is prepared from benzene as a raw material by first treating 
pure benzene with strong sulphuric acid and heating the mixture in 
jacketed iron kettles provided with agitation at a temperature of 
about 90° C. (194° F.) for several hours. The resulting benzene sul- 
phonate is usually treated with lime, which converts it to calcium 
benzene sulphonate, which, in turn, is converted to sodium benzene 
sulphonate by means of sodium carbonate (soda ash). The sodium 
benzene sulphonate is dried and heated in fusion kettles with caustic 
soda which converts it into sodium phenate. The fusion mixture is 
dissolved in water and treated with either carbon dioxide or sulphuric 
acid, which causes the phenol to separate out as a distinct layer. This 
layer is drawn off and distilled in order to separate the pure phenol 
from water and other impurities. Pure phenol is a white crystalline 
solid which melts at about 40° C. (104° F.). 

For conversion to picric acid the phenol is melted into large jack- 
eted iron kettles and treated with sulphuric acid of about 93 per 
cent strength, the mixture heated with stirring at a temperature of 
about 95° C. (203° F.) from four to six hours. The resulting phenol 
sulphonic acid is diluted with water and treated in a large acid-proof, 
brick-lined nitrator with 42° Baume nitric acid (about 70 per cent). 
The reaction generates heat, and the mixing is therefore carried on 
very slowly, the maximum temperature being about 110° C. After 
cooling the mixture the crystallized picric acid is separated from the 
spent acid on a vacuum filter, washed with water, and dried. 

Chlorbenzol 'process. — Although this process has been quite exten- 
tively used abroad, its use in this country has been rather limited. 
Briefly the process involves, first, the treatment of benzene with 
gaseous chlorine, whereby monochlorbenzene results. This product 
is purified by distillation, and then nitrated with a mixture of nitric 
and sulphuric acids to give dinitrochlorbenzene. The latter on treat- 
ment with lime or soda loses its chlorine and becomes calcium or 
sodium dinitrophenolate, which on acidifying is converted to dinitro- 
phenol. The dinitrophenol is readily nitrated to picric acid (trinitro- 
phenol) by means of nitric and sulphuric acids. 

Catalytic process. — The catalytic process is only in its experimen- 
tal stage in this country. It consists in converting benzene into either 
dinitrophenol or picric acid direct in one operation by means of weak 
nitric acid in the presence of mercury nitrate which acts as a cata- 
lyst. The weak nitric acid first oxidizes the benzene to phenol, which 
then combines with nitric acid to give di- and tri-nitrophenols. 



118 MILITARY EXPLOSIVES. 

USE. 

The fact already noted, that picric acid combines readily with 
practically all metals to form picrates which are unduly sensitive to 
friction, shock, or heat has been detrimental to the use of picric acid 
for military purposes, in spite of the fact that it is a stronger explo- 
sive than T. N. T. When a non-metallic lining is used for the shell 
cavity, as for instance, certain lacquers, varnishes or paints, the 
danger of the formation of these salts is obviated to a great degree. 
It may be mentioned in this connection that picric acid has certain 
distinct advantages over ammonium picrate, for example, while the 
repressing of ammonium picrate is a dangerous practice, with picric 
acid the contrary is the case, for the insensitiveness is increased within 
certain limits. The introduction of T. N. T. as a military explosive 
has resulted in the gradual abandonment of picric acid by practically 
every country except France, where it has been very largely used 
during the war. In the United States it has been used only for con- 
version into "explosive D" or ammonium picrate, which is largely 
used in base-fuzed shell for seacoast cannon. Picric acid has also 
found use as a booster explosive and even as a substitute for part 
of the mercury fulminate charge in detonators. It has been used to a 
limited extent as a component of many explosive mixtures proposed 
or patented for military or commercial use. 

INSPECTION. 

Specifications. — The chemical requirements prescribed for picric 
acid by Ordnance Department specifications are as follows: 
It must have a solidification point of not less than 120° C. 
It must not contain — 

(a) More than 0.2 per cent moisture if purchased as dry picric 
acid or 12 per cent if purchased as wet picric acid. 

(b) More than 0.1 per cent sulphuric acid, both free and combined. 

(c) More than 0.2 per cent ash. 

(d) More than 0.2 per cent matter insoluble in water. 

(e) More than 0.0004 per cent soluble lead. 
(/) Free nitric acid. 

Color, lemon yellow. 

Fineness, 12 mesh (screen openings 0.058 inch, wire 0.025 inch). 

Analysis and testing. — The methods prescribed for testing are as 
follows : 

Solidification point: A sample of the picric acid to be used for 
this test must be dried to constant weight at a temperature not ex- 
ceeding 50° C. The sample is melted in a test tube 6 inches long 
and three-fourths of an inch in diameter, immersed in a bath of 
glycerine. Sufficient picric acid is taken to give a 3-inch column 



MILITARY EXPLOSIVES. 119 

of the molten material in the test tube. The glycerine bath is kept 
at a temperature of 130° C. A standardized thermometer graduated 
in 0.1 of a degree is placed in the tube when the picric acid is com- 
pletely melted and the tube removed from the glycerine bath and 
stirred until sample solidifies. At this point the temperature will 
remain constant for an appreciable length of time and finally 
slightly rises. The highest temperature reached on such rise is noted 
as the solidification point. 

Moisture: Dry a known weight, approximately 10 grams, spread 
thinly on a tared watch glass or dish, 4 hours at 70° C, or to con- 
stant weight. 

Sulphuric acid : Dissolve a known weight, approximately 2 grams, 
in 50 c. c. of distilled water. Acidify with hydrochloric acid, and 
then heat. Add hot barium chloride solution slowly with constant 
stirring and filter while hot on a tared Gooch. Wash thoroughly 
with hot distilled water, dry to constant weight at 100° C, and 
weigh. Calculate results as sulphuric acid in original sample. 

Nitric acid : Test a water solution of picric acid with a solution 
of diphenylamine in concentrated sulphuric acid. No coloration 
should result. 

Ash : Weigh a sample of approximately one gram in a platinum 
crucible, saturate with melted paraffin, and burn off cautiously. 
Ignite residue, cool and weigh. 

Insoluble matter: Dissolve 10 grams of the sample in 150 c. c. of 
boiling water, continue boiling for 10 minutes, filter while hot 
through a tared Gooch, wash thoroughly with hot water, and dry 
to constant weight at 100° C. 

Soluble lead: Place a known weight, approximately 300 grams of 
the picric acid, in a 2-liter flask and allow to soak in 100 c. c. of a 
hot saturated solution of barium hydroxide in 65 per cent alcohol. 
Shake well and add 1,400 c. c. of 95 per cent alcohol and digest at a 
temperature below the boiling point of alcohol until all the picric 
acid has been dissolved with the exception of small particles of in- 
soluble matter. Shake the solution thoroughly and allow to stand 
in the cold until most of the picric acid has crystallized out, and filter. 
It is not necessary to disturb the crystalline picric acid at the bottom 
of the flask as only 500 c. c. of the solution is used for the comple- 
tion of the tests and this amount can be decanted. Take 500 c. c. 
of this filtered solution which represents 100 grams of picric acid. 
Add 4 or 5 drops of nitric acid and 10 c. c. of a 1 per cent mercuric 
chloride solution and pass a slow stream of hydrogen sulphide 
through this solution for 15 minutes. Allow to settle 20 minutes, 
filter and wash with alcohol saturated with hydrogen sulphide. Dry 
the filter paper and ignite in a porcelain crucible. Add 9 c. c. of 



120 MILITARY EXPLOSIVES. 

nitric acid, specific gravity of 1.42, and warm on a hot plate. Then 
add enough warm water to make up the volume to 50 c. c. Elec- 
trolize at 0.4 ampere and 2y 2 volts, temperature 65° C. After one 
hour, wash electrode by replacing the beaker with another one full 
of distilled water without interrupting the current. Dry and weigh 
the tared anode. The weight of lead peroxide found by difference 
multiplied by 0.8661 gives the per cent of soluble lead. 

STORAGE. 

The rules governing the storage of dry picric acid are the same 
as those which apply to the storage of black powder, dynamite, and 
dry guncotton. Wet picric acid being considered less hazardous, 
falls under the same classification as T. N. T. and ammonium picrate. 
The dimensions of the magazines in either case should not exceed 
42 by 26 feet. They should be of the ordinary hollow tile con- 
struction, and the walls in the latter case (that of wet picric acid) 
filled with sand. It is necessary that all dust accumulating from dry 
picric acid should be carefully removed from any point in or around 
the buildings, conveyers, or cars. Although dust originating from 
this source is not as dangerous as that from black powder, it is 
nevertheless a matter of record that serious explosions have been 
caused from this source. Powder shoes must be worn in every 
instance where dry picric acid is being handled. 



CHAPTER X. 
NITROSTARCH EXPLOSIVES. 

GENERAL NATURE. 

Under this classification are included "Trojan grenade explosive," 
"Trojan trench mortar shell explosive," and " grenite." These ex- 
plosives are frequently referred to as " nitrostarch," but it should be 
noted that up to this time pure nitrostarch has not been used as 
either a military or a commercial explosive, the nearest approach 
to it for military purposes being "grenite," which is -about 95 per 
cent nitrostarch with the addition of binding material added for 
the purpose of granulating. The two Trojan explosives, which are 
practically identical in composition, contain only approximately 
40 per cent nitrostarch, together with ammonium nitrate, sodium 
nitrate and small amounts of materials added for the purpose of 
stabilizing, reducing sensitiveness and hygroscopicity, and neutraliz- 
ing any possible acidity of other ingredients. 

REASONS FOR ADOPTION. 

These nitrostarch explosives were adopted by the Ordnance De- 
partment mainly for the reason that at the time the United States 
entered the Avar a decided shortage of T. N. T., owing to deficient 
toluol supply, was indicated. A thorough investigation showed 
that nitrostarch explosives, properly manufactured, seemed to be 
not only entirely suitable for trench warfare purposes, but to offer 
certain advantages over T. N. T., namely, low cost, insensitiveness 
to rifle bullet fire and to friction or impact, ample supply of raw 
materials, etc. 

MANUFACTURE. 

Nitrostarch is prepared by treating starch with a mixture of nitric 
and sulphuric acids, just as nitrocellulose results from similar treat- 
ment. It can be prepared from any variety of starch, but it is 
claimed that cassava or tapioca starch gives a slightly more stable 
product than ordinary corn starch. The starch must first be freed 
from impurities such as fats and oils and water-soluble matter, then 
carefully dried at low temperatures, screened, etc. It is fed slowly 
into the acid mixture in an iron nitrator provided with suitable 
agitation and cooling surface, in order to avoid overheating from 
violent local action. This treatment converts the starch into starch 

121 



122 MILITARY EXPLOSIVES. 

nitrate (commonly but incorrectly referred to as nitrostarch), with- 
out any change in appearance, but a decided change in chemical 
properties. 

The nitrated product is separated from the excess of spent nitrat- 
ing acid, drowned in water, washed thoroughly to remove all traces 
of free acid, then separated from the water in filters or centrifugal 
wringers, and finally spread out on trays to dry in suitable dry 
houses heated with warm air to a temperature not exceeding approx- 
imately 35° to 40° C. (about 100° F.). 

The drying operation, especially the handling of the warm, dry 
product, is the only really dangerous operation connected with the 
manufacture, the dry nitrostarch being highly inflammable, capable 
of being ignited by the slightest spark such as might result from a 
static charge, and when once ignited, burning with explosive violence. 

The mixing of the dry nitrostarch with the " dope " materials, as 
the inert ingredients of such explosive mixtures are frequently called, 
is a simple operation, carried out in large revolving mixing barrels. 
All of the " dope" materials must first be ground to the proper de- 
gree of fineness and dried to the proper moisture content, so that the 
moisture content of the finished explosive will not be in excess of 
the prescribed amount. Granular nitrostarch explosives, such as 
" grenite," are usually prepared by spraying the dry material with a 
solution of the binding material while the mixture is being agitated 
in a revolving mixer. The resulting granules are dried and screened 
to proper size. 

CHEMICAL AND PHYSICAL PROPERTIES. 

Nitrostarch itself is a white, finely divided material, quite similar 
in appearance to ordinary powdered starch. When observed even 
under the microscope there is no appreciable difference between 
nitrated and unnitrated starch until the granules are treated with 
iodine, which colors the unnitrated starch blue but does not affect 
the nitrated product. 

Nitrostarch is insoluble in water and does not gelatinize or form 
a paste when heated with water, thereby differing from starch. Its 
solubility in alcohol and in mixtures of alcohol and ether depends 
on its percentage of nitrogen or the extent to which it has been 
nitrated. The grade of nitrostarch ordinarily employed contains 
from about 12.50 to 12.75 per cent nitrogen; that prescribed for 
military purposes contains at least 12.80 per cent. All nitrostarch 
is readily soluble in acetone, the solubility in ether alcohol, in gen- 
eral, increasing as the nitrogen content decreases. It has no great 
tendency to absorb moisture from the atmosphere beyond the amount 
of 1 to 2 per cent. 



MILITARY EXPLOSIVES. 123 

Trench grenade or trench mortar shell explosive differs greatly in 
appearance and certain of its properties from straight nitrostarch, 
being of grayish-black color and of about the consistency of ordinary 
brown sugar, having a slightly clamp feel and tendency to pack under 
compression, due to the small amount of mineral oil contained as an 
ingredient. This oil, besides decreasing the sensitiveness of the 
explosive to ignition and to shock or friction, helps to reduce its 
attraction for moisture, the mixture of ammonium nitrate and sodium 
nitrate which it contains being very hygroscopic. In spite of this 
coating of oil, the Trojan explosive, when spread out in a thin layer 
in a damp atmosphere, will absorb moisture to such extent that it 
becomes decidedly wet. Under ordinary working conditions, how- 
ever, there is no difficulty in loading this explosive and in avoiding 
the absorption of an undesirable amount of moisture. 

Grenite, which is almost entirely pure nitrostarch with the addi- 
tion of a small amount of oil and a binding material, differs greatly 
in appearance from Trojan explosive, being in the form of small 
white, hard granules which run freely without sticking together. 
Since it contains no ammonium nitrate or other hygroscopic ma- 
terials, grenite has no particular tendency to absorb moisture even 
in damp atmospheres. 

SENSITIVENESS. 

Pure dry nitrostarch is more sensitive to impact than T. N. T. but 
less sensitive than dry guncotton or nitroglycerin. As mentioned 
above, it is highly inflammable and readily ignited by the slightest 
spark such as may result from friction, and, like black powder, burns 
with explosive violence. It is readily detonated by a inercury ful- 
minate detonator. 

Trojan explosive and grenite are both much less sensitive than 
straight nitrostarch, being required to pass the pendulum friction test 
of the United States Bureau of Mines and the rifle bullet test, when 
packed in pasteboard containers. In heavy metal containers these 
explosives frequently ignite and burn when penetrated by a rifle 
bullet and in rare instances have exploded under this test. 

Trojan explosive is especially insensitive to ignition, being rather 
difficult to ignite with the flame of a match when spread out uncon- 
fined. When once ignited, however, especially in any quantity, it 
burns fiercely, with a light-colored smoke. 

Nitrostarch explosives are readily detonated by mercury fulminate 
detonators, a No. G detonator, containing one grain of fulminate 
composition, producing complete detonation, unless the explosive has 
been rendered unduly insensitive by the absorption of excessive mois- 
ture or by other cause. 



124 MILITARY EXPLOSIVES. 

An important consideration in the case of military explosives, 
especially those intended for trench warfare purposes, is their sensi- 
tiveness to explosion by influence ; that is, their tendency to detonate 
from the shock of a near-by explosion. The Trojan explosive has been 
found especially insensitive to such effects, as shown by the following 
tests : 

Three malleable iron hand grenades were loaded with Trojan 
grenade explosive, and packed in a small wooden box divided by 
means of light wooden partition into three compartments, into each 
of which a grenade fit snugly in upright position. The two grenades 
in the end compartments were provided with plugs closing the filling 
holes and the center grenade with a No. 6 detonator and black powder 
fuse, the fuse passing out through a small hole in the wooden cover 
of the box. The center grenade was then detonated by means of the 
detonator and fuse. On collecting the fragments it was found that, 
while the center grenade had been broken into hundreds of small 
fragments indicating normal detonation, the adjacent ones had been 
merely broken into several large pieces by the force of this explosion, 
a large part of the powder in them being recovered unconsumed, 
indicating that only the central grenade had detonated. 

In another test, fifteen 3-inch Stokes trench mortar shells were 
loaded with Trojan explosives, and packed in the usual manner — 
three in each of five of the regular wooden shipping cases. These 
cases were placed on end in a row, broad sides in contact, in a pit 5 
feet deep, and the pit filled with earth. A fuse and detonator were 
inserted in the shell farthest removed from the center of this 
assembly. The detonation of this shell was complete, as indicated 
by the fragments dug out of the small crater produced. Of the 
other 14 loaded shell, 9 were recovered uninjured, 1 was broken 
into several large fragments indicating a low order of explosion, 
and the remaining 4 were merely split open by the shock of the 
adjacent explosion, the explosive contained in them having been 
burned. A similar test of 15 shells loaded with 50/50 amatol re- 
sulted in complete detonation of the 15 shells, as indicated by the 
fact that a very large crater was produced and no unexploded shell 
or large fragments recovered. 

STABILITY. 

Early attempts to manufacture nitrostarch resulted in the produc- 
tion of material which was decidedly unstable, and numerous state- 
ments found in the literature of explosives refer to nitrostarch as 
being unsatisfactory for use as an explosive because of sensitiveness 
and instability. The manufacturers in this country, however, sue- 



MILITARY EXPLOSIVES. 125 

ceeded a number of years ago in placing on the market nitrostarch 
explosives which proved highly satisfactory in these respects and 
found considerable application as blasting explosives. More recent 
developments led to a product which entirely met the strict require- 
ments prescribed for military explosives, and there is every reason 
to believe that the nitrostarch explosives adopted by the Ordnance 
Department have excellent keeping properties if properly stored in 
dry atmosphere at reasonable temperatures. 

The Trojan explosive, however, if allowed to absorb undue quan- 
tities of moisture, especially in a warm atmosphere, may tend to de- 
teriorate owing to gradual decomposition. Such deterioration can- 
not result in a dangerous condition because it is accompanied by a 
continual loss of explosive strength and sensitiveness. 

EXPLOSIVE PROPERTIES. 

Pure nitrostarch detonates, when properly compressed, at a rate 
of probably at least 20,000 feet per second. In the case of Trojan 
explosive, containing only about 25 per cent nitrostarch, the rate of 
detonation is lower but the large gas volume and energy content 
makes this explosive quite suitable for the purpose, as is indicated 
by the result of fragmentation tests simulating as nearly as possible 
service conditions. 

In judging the suitability of a grenade explosive from the results 
of fragmentation tests, consideration is given to the number of frag- 
ments of an "effective" size, rather than to the total number of frag- 
ments, for the reason that it is considered that the smaller frag- 
ments would have an almost negligible effect against personnel. As 
a result of actual penetration tests it has been concluded that frag- 
ments which pass through a screen having two openings to the linear 
inch and are retained on a screen having four openings to the linear 
inch can be considered as the most effective and in reporting the 
results of fragmentation tests these fragments are sometimes desig- 
nated as "effective" fragments. 

Fragmentation results in grenades vary over a considerable range, 
depending on the exact qualities of the metal. With a charge of 
approximately 2.5 ounces of Trojan grenade explosive the "effective" 
fragments will vary from about 100 to 150 and total fragments from 
200 to 500. Grenite, being nearly pure nitrostarch, gives greater 
fragmentation, about IV2 ounces of the explosive giving fragmen- 
tation equal to the 2.5 ounce charge of Trojan powder. A charge 
of 2!/2 ounces of T. N. T. gives fragmentation only slightly inferior 
to that of the Trojan powder. 



126 MILITARY EXPLOSIVES. 

In general, it may be said that the nitrostarch explosives are ap- 
proximately equal to T. N. T. or 40 per cent dynamite in explosive 
strength. 

USE, MILITARY AND COMMERCIAL. 

The Trojan nitrostarch explosive has been used as the bursting 
charge for hand grenades, rifle grenades, and Stokes trench mortar 
shell. It is well adapted to such purposes but has not been con- 
sidered for use as a bursting charge for high explosive gun shell. 
Its physical consistency is such that it must be loaded into grenades 
through the small filling hole, by means of vibrating machines, the 
explosive being "jarred" into the grenade through small funnel open- 
ings. Trench mortar shell are loaded by hand-stemming and have 
also been loaded with the Trojan explosive by means of a screw-filling 
machine. 

Grenite has been approved only for grenades and is considered too 
sensitive for use as a trench mortar shell explosive. Being granular 
and " free-running " it is readily loaded into the grenades through 
funnel openings, no attempt being made to pack it to a high density. 

Nitrostarch has been considered for the manufacture of smokeless 
propellant powder, and numerous attempts have been made to de- 
velop a satisfactory powder of this type, but the problem can not as 
yet be considered solved. 

Nitrostarch explosives similar to Trojan grenade explosive have 
been used for a considerable number of years as blasting explosives 
for use in mining, quarrying, and other engineering operations, and 
have met with considerable success as substitutes for the more ex- 
pensive nitroglycerin explosives. Among the numerous advantages 
of nitrostarch explosives may be noted the fact that, unlike nitro- 
glycerin explosives, the}' are nonfreezing. 

CARE IN STORAGE AND HANDLING. 

The storage of nitrostarch explosives in general is mainly a fire 
risk. That is to say, the danger accompanying storage is more one 
of fire than of explosion. Burning may, however, proceed at such 
rate as to be almost explosive in nature, and the fact that nitrostarch 
can be exploded by impact must not be overlooked. 

Storage magazines must be kept at as low temperatures as possible 
in order to avoid as much as possible the tendency of nitrostarch to 
undergo decomposition on heating. A reasonably dry atmosphere in 
magazines is also highly essential, as Trojan explosive especially, on 
account of its ammonium nitrate content, has a considerable affinity 
for moisture. 

There is no danger. of poisoning of any kind connected with the 
handling of nitrostarch explosives. 



MILITARY EXPLOSIVES. 



127 



INSPECTION. 



Specifications. — The chemical composition of Trojan explosive as 
prescribed by Ordnance Department specifications is as follows : 





Not less 
than — 


Not more 
than — 


Nitrostareh 


Per cent. 

23.0 

31.0 

36.0 

1.5 

.5 

.5 

.2 


Per cent. 
27 


Ammonium nitrate 


35 


Sodium nitrate 


40.0 


Charcoal 


2 5 


Heavy hydrocarbons 


1 5 


Antiacid 


1 5 


Diphenvlamine 


4 


Moisture 


1 2 









Tne chemical composition of grenite is prescribed as follows: 





Not less 
than — 


Not more 
than — 


Nitrostareh 


Per cent. 
95.5 
.75 
.75 


Per cent. 
98 25 


Petroleum oil 


2 00 


Gum arabic 


2 00 




1 00 









METHODS OF ANALYSIS. 

The Ordnance Department specifications prescribe the following 
method for the analysis of Trojan explosive: 

(a) Moisture: Approximately 5 grams of the sample, accurately 
weighed out, shall be spread evenly on a 90 mm. watch glass (3^ 
inches diameter) and placed in a desiccator over concentrated sul- 
phuric acid. Loss in weight after 48 hours is taken as moisture. As 
an alternative method, a vacuum desiccator may be used with sul- 
phuric acid (specific gravity, 1.84) as a desiccating agent and em- 
ploying a vacuum of at least 700 mm. of mercury. After 24 hours 
the vacuum shall be slowly relieved and the loss in weight taken as 
moisture. The percentage of moisture shall not exceed 1.2 per cent. 

(b) Ether extract: Approximately 10 grams of the sample are ac- 
curately weighed out and placed in a porous crucible (Gooch crucible, 
with thin asbestos mat, or an alundum filtering crucible) and ex- 
tracted with pure petroleum ether of 0.640 to 0.660 specific gravity. 
After complete extraction, the crucible and contents are dried by 
means of a stream of dry air until complete removal of the petroleum 
ether, after which the crucible shall be placed in a steam oven and 
dried, to constant weight at approximately 70° C. The difference in 
weight between the original weight of the sample, after deducting 
weight of moisture, and the weight after extraction is taken as the 
heavy hydrocarbon oil present, together with the diphenylamine. 
The diphenylamine in this mixture may be determined by means of 
Mie Dumas method "for determining nitrogen. 



128 MILITARY EXPLOSIVES. 

(c) Water extract: The material in the crucible after removal of 
the heavy oil consists of nitrostarch, ammonium nitrate, sodium ni- 
trate, charcoal, and sodium bicarbonate. By treatment with warm 
distilled water, the ammonium nitrate, sodium nitrate, and sodium 
bicarbonate are removed, and the material in the crucible after drying 
at 80° C. for several hours consists of nitrostarch and charcoal. The 
loss in weight in the water extraction is determined and also the 
weight of the crucible plus nitrostarch and charcoal. These two 
factors are then used in the subsequent calculations. 

(d) Sodium bicarbonate: The water extract is made up to a fixed 
volume. One portion is taken for the determination of the sodium 
bicarbonate present. This is determined by titration with N/10 sul- 
phuric acid, using methyl orange as an indicator, and the alkalinity 
so found is calculated to sodium bicarbonate. 

(e) Ammonium nitrate: At the option of the inspector, the per- 
centage of ammonium nitrate is determined by taking an aliquot 
portion of the water extract, adding caustic soda until the solution 
is strongly alkaline, and then distilling in an apparatus as used for 
ammonia determinations and collecting the distillate in a known 
volume of standard sulphuric acid. The excess acid is titrated with 
standard alkali, methyl orange being used as an indicator, and the 
result is then calculated to ammonium nitrate. 

(f ) Sodium nitrate : An aliquot part of the water extract is acidi- 
fied with nitric acid and the solution evaporated to dryness in a plati- 
num dish. It is then ignited at a low red heat over a suitable flame, 
using care to avoid loss of the contents. The weight is then taken 
and a correction made for the amount of sodium bicarbonate present 
and the results regarded as sodium nitrate present. Following this 
procedure, the ammonium nitrate would be taken by difference, in 
order to avoid the determination of ammonia. 

(g) Charcoal: The residue in the crucible after the water extrac- 
tion consists of nitrostarch and charcoal. This material is best ex- 
tracted in a Wiley extractor with warm acetone until no further solu- 
ble material is obtained. The crucible is then dried in a stream 
of dry air and further dried for several hours at 100° C. The weight 
of the charcoal is taken as the increase in weight of the crucible over 
its original weight empty. 

(h) Nitrostarch: The difference between the sum of nitrostarch 
and charcoal content as determined in paragraph (<?), and the per- 
centage of charcoal as found by paragraph (g), represents the nitro- 
starch present. 

The analysis of grenite is carried out in a similar manner, the ether 
extraction removing the oil, the water extraction dissolving the 
gum arabic and leaving the nitrostarch. 



CHAPTER XI. 

TETRYL. 

The high explosive commonly known as tetryl (sometimes as tetra- 
lite or pyronite) is designated by the chemist as tri-nitro-phenyl- 
methyl-nitramine and also frequently improperly called tetra-nitro- 
methyl-aniline. It is closely related to T. N. A. (tetra-nitroaniline), 
resembles it in many of its properties, and is used for similar pur- 
poses. 

MANUFACTURE. 

Tetryl is a derivative of benzene and is therefore in the same class 
of aromatic nitrocompounds as T. N. T. and T. N. A. Although the 
explosive manufacturer usually starts with dimethylaniline as his 
raw material, the entire process, beginning with benzene, is indicated 
as follows: Benzene is nitrated to nitrobenzene by means of a mix- 
ture of nitric and sulphuric acids and the resulting nitrobenzene re- 
duced with iron filings and hydrochloric (muriatic) acid to aniline. 
Aniline is then combined with methyl alcohol (wood alcohol) by 
heating these ingredients under pressure in the presence of sulphuric 
acid or iodine, yielding dimethylaniline. 

The dimethylaniline is a yellowish oily liquid of slightly lower 
specific gravity than water. Prior to nitrating it is dissolved in a 
large excess of 98 per cent sulphuric acid because if treated direct 
with mixed acid a very violent reaction results. This solution in sul- 
phuric acid is now added to the mixture of nitric and sulphuric acids 
in a nitrator provided with means for cooling and agitation. The 
mixing is carried on very slowly in order to avoid overheating and 
possible explosion. 

The tetryl separates out from the acid mixture and is freed from 
the acid by filtration and washing with water, after which it is dried 
in a current of warm air until its moisture content is not more than 
0.05 per cent. 

CHEMICAL AND PHYSICAL PROPERTIES. 

Tetryl is a fine crystalline powder of a yellow color, practically 
insoluble in water, but soluble in acetone, benzene and other solvents. 
It is readily recrystallized and can therefore be obtained in very pure 
condition if desired. It melts, when pure, between 129° and 130° C. 
Tetryl is poisonous when taken internally, and precaution is neces- 
132569—19 11 129 



130 MILITARY EXPLOSIVES. 

sary in its manufacture, especially as regards the dust encountered 
in handling and packing the dry material. With the exception of 
T. N. A., it has a higher nitrogen content (24.4 per cent) than any 
other military explosive. 

STABILITY AND SENSITIVENESS. 

Tetryl is stable at all temperatures which may be met with in 
storage. When heated above its melting point it undergoes gradual 
decomposition and explodes at about 186° C. (335° F.). It is more 
sensitive to shock or friction than T. N. A., being of about the same 
order of sensitiveness as picric acid. It is more sensitive to detona- 
tion by means of mercury fulminate than is T. N. T., resembling 
T. N. A. in this respect. Like T. N. A., it is also readily exploded by 
the penetration of a rifle bullet. 

Unlike T.N. A., tetryl does not undergo decomposition when 
heated with water at temperatures somewhat higher than ordinary 
storage temperatures. 

EXPLOSIVE PROPERTIES. 

Tetryl has been found to have a rate of detonation of about 24,000 
feet per second — practically the maximum rate obtained with T. N. T. 
Strength tests, such as the Trauzl lead block test, show tetryl to be 
stronger than any other military high explosive, the average expan- 
sion produced in the lead block for the more common high explosives 
being as follows : 

T. N. A., 380 cubic centimeters. 

Tetryl, 320 cubic centimeters. 

Picric acid, 300 cubic centimeters. 

T.N.T., 260 cubic centimeters. 

USE, MILITARY AND COMMERCIAL. 

The high explosive strength and quickness (or "brisance") of 
tetryl would seem to adapt it for use as a bursting charge, but its 
sensitiveness to mechanical shock is such that if used as a shell filler 
it would not withstand the shock of discharge of the gun. It is. 
however, sufficiently insensitive so that when highly compressed into 
a booster it is perfectly safe. In this condition it is readily deto- 
nated by the charge of mercury fulminate in the fuze of the shell, and 
the violence of its detonation insures a high order of detonation of 
the bursting charge. 

Tetryl is therefore generally adopted in this country as a booster 
explosive either alone or combined with T. N. T. (Grade I), the two 
explosives being usually loaded separately into the booster casing, in 



MILITARY EXPLOSIVES. 131 

the form of highly compressed pellets perforated with a central hole 
of suitable size for the detonator of the fuze. 

It is also used in detonators for both military and commercial pur- 
poses, as a partial substitute for the mercury-fulminate charge, the 
tetryl being pressed into the bottom of the detonator shell, covered 
with a small priming charge of fulminate and the entire charge 
partly confined by a perforated inner capsule of copper. 

PRECAUTIONS TO BE OBSERVED IN HANDLING AND STORAGE. 

The same precautions should be observed in the handling and 
storage of tetryl as in the case of other sensitive high explosives. It 
should be kept dry because moisture interferes with its effectiveness. 
It must be properly protected from bullet fire in brick or hollow tile 
magazines with iron doors and window shutters. Detonators, blast- 
ing caps, fuzes, dynamite, etc., must not be stored w 7 ith tetryl. Rub- 
ber-soled shoes should be worn in magazines and every precaution 
taken to prevent ignition or explosion from friction or blows due 
to rough handling. 

INSPECTION. 

/Specifications. — Ordnance Department specifications require that 
tetryl shall have the following properties : 

(a) Melting point — not less than 128° C. 

(b) Acidity — not more than 0.01 per cent (as H 2 S0 4 ). 

(c) Insoluble in acetone — not more than 0.30 per cent. 

(d) Ash — not more than 0.15 per cent. 

(e) Moisture and other volatile matter — not more than 0.05 per 
cent. 

(/) Sodium salts — not more than trace. 

(g) Color — light yellow. 

(h) Fineness — 12-mesh (screen openings 0.058 of an inch, ware 
0.025 of an inch). 

Methods of testing — The prescribed methods of testing tetryl for 
acceptance are as follows: 

Melting point: Fifteen grams of tetryl which have been dried 24 
hours in a vacuum desiccator over calcium chloride are ground in a 
mortar to pass a 40-mesh screen and quartered. A quarter is ground 
to pass a 100-mesh screen, the latter material being used in the test. 
The capillary tubes used for making the test must be of uniformly 
fine bore. A standardized thermometer shall be used and correc- 
tions made for emergent stem. In charging the capillary, the tube 
should be filled to approximately one-fourth inch from the bottom 
and the material in the capillary placed opposite the center of the 
bulb of the thermometer. Efficient agitation must be provided for 



132 MILITARY EXPLOSIVES. 

the bath, and the temperature of the bath raised rapidly until ap- 
proximately 120° C. From this point the rate of heating is adjusted 
so that the temperature increases at the rate of not more than 1° 
in 3 minutes. The melting point shall be taken at the appearance of 
the first meniscus across the tube. 

Acidity: A known weight of the ground sample, approximately 
10 grams, is shaken for 5 minutes in 50 c. c. of boiled distilled water. 
The solution is then filtered and washed with not more than 50 
c. c. of boiled distilled water. The filtrate is titrated with N/50 
sodium hydroxide solution, using phenolphthalein as an indicator 
and results calculated as sulphuric acid. 

Insoluble matter : A known weight, approximately 10 grams of the 
sample, is dissolved in 75 c. c. of acetone and filtered through a tared 
Gooch. The residue in the crucible is washed with not less than 25 
c. c. of acetone and dried for 4 hours at 100° C. and weighed. 

Ash: The dried Gooch crucible, containing the residue insoluble 
in acetone, is carefully ignited, cooled in a desiccator and weighed. 

Moisture and volatile: A known weight, approximately 10 grams 
of the sample, is dried in a shallow glass jar or dish for 24 hours 
over sulphuric acid and then weighed. The material should be thinly 
spread, in no place being over 0.5 cm. in height. The jar or dish is 
covered within air-tight cover during all weighings. 

Sodium salts: Ten grams dry tetryl are boiled in 50 c. c. of dis- 
tilled water, cooled, filtered, and the filtrate acidified with acetic acid 
and evaporated to a 10 c. c. volume, cooled and filtered. The filtrate 
is made alkaline with ammonium hydroxide and 5 c. c. of a 10 per 
cent solution of ammoniacal copper sulphate added. No crystals of 
cupro ammonium picrate shall be separated after five minutes' 
standing. 



CHAPTER XII. 

TETRANITROANILINE (T. N. A.)- 

Tetranitroaniline, commonly known by the abbreviation T. N. A., 
is a high explosive derived from benzene, the process of manufac- 
ture and use of which in this country is patented by Dr. B. J. 
Flurscheim, an English chemist, under United States Patents Nos. 
1,045,011 and 1,045,012, November 19, 1912, and No. 1,074,545, Sep- 
tember 30, 1913. 

MANUFACTURE. 

It is manufactured by a rather complicated process, beginning with 
benzene as a raw material. Benzene is first nitrated by means of a 
mixture of nitric acid and sulphuric acid to dinitrobenzene (D. N. B.) , 
which, in turn, is converted by treatment with a solution of sodium 
sulphide to metanitraniline (M.N. A.); the metanitraniline, on 
treatment with sulphuric acid, is converted to metanitraniline sul- 
phate (M. N. A. S.), which is finally nitrated by means of a mixture 
of strong nitric and sulphuric acids to tetranitroaniline (T.N. A.). 
In this final nitration, the M. N. A. S. is dissolved in a large excess 
of strong sulphuric acid, and a mixed acid added with stirring and 
cooling. The finely crystalline T. N. A. separates out from the acid 
mixture as the reaction proceeds, and is finally recovered by filtra- 
tion, washed thoroughly with water to remove all free acid, filtered 
again from the water and finally dried in a current of air at a low 
temperature. 

CHEMICAL PROPERTIES. 

T.N. A. is generally admitted to be practically the strongest of 
all solid high explosives. It is a finely crystalline material vary- 
ing in color from greenish yellow to olive green, the fine crystals, 
which appear under the miscroscope as square plates, being small 
enough to pass through a sieve of about 80 mesh to the linear inch. 
Owing to the fact that it has no tendency to absorb moisture from 
the atmosphere, it does not cake in containers. 

When dry, T. N. A. is not in the least affected by exposure for 
considerable periods to temperatures as high as even 75° C. ; in fact, 
such treatment improves its apparent stability as indicated by the 
usual "heat test" with potassium iodide — starch paper — for the 
reason that such heating probably eliminates traces of acid impuri- 
ties. When moist, however, heating at temperatures as low as 50° 

133 



134 MILITARY EXPLOSIVES. 

C. (122° F.) will cause a very gradual decomposition of T.N. A., 
which, however, is not of a dangerous nature, but probably only re- 
sults in a loss of explosive strength. Traces of acid decomposition 
products are liberated by such treatment. 

T. N. A. when properly manufactured and thoroughly dried passes 
satisfactorily all of the usual tests for stability, including the 65.5° 
C. heat test and the 135° C. test. 

Like T. N. T., T. N. A. has no action on metals with which it may 
be in contact, differing in this respect from picric acid, which tends 
to form metallic salts with almost all metals. 

T. N. A. is practically insoluble in water, but readily soluble in 
acetone. It melts only at a temperature of about 210° to 215° C.,and 
then only with decomposition. On heating rapidly to higher tem- 
peratures it undergoes rapid decomposition or deflagration with 
flame, but does not detonate. It contains a higher percentage of 
nitrogen than any of the well-known military explosives — 25.6 per 
cent, as compared with 24.4 per cent for tetryl, 18.5 per cent for 
T. N. T., and 18.3 per cent for picric acid. 

TOXIC PROPERTIES. 

Although the manufacture of T. N. A. involves the preparation of 
intermediate products which are of a poisonous nature, such as 
dinitrobenzene and metanitroaniline, T. N. A. itself is not poisonous. 
This has been demonstrated by experimentation in which T. N. A. 
was administered internally to small animals with no bad results. 
In contact with the skin it produces yellow stains, similar to that 
resulting from picric acid, but no poisoning results from this. 

SENSITIVENESS TO HEAT, SHOCK, AND DETONATION. 

Mention has already been made of the fact that T. N. A. melts only 
at very high temperatures (210° to 215° C.) and then only with de- 
composition. It is therefore obvious that this explosive, unlike 
T. N. T., is never used in cast form, but always in its original crystal- 
line condition or highly compressed. 

T. N. A. is, in general, more sensitive to the shock of blows or fric- 
tion than is T. N. T., although the difference in the sensitiveness of 
these two explosives is not great. For example, in one series of tests 
it was found that T. N. T. detonated under a 200-kilogram (about 
440 pounds) drop weight with a fall of 120 centimeters (48 inches), 
while under the same conditions T. N. A. detonated under the effect 
of a drop of 100 centimeters (40 inches). It is to be noted, however, 
that the detonation produced in T. N. A. by such means invariably 
spreads through the entire quantity of explosive, while with T. N. T. 



MILITAKY EXPLOSIVES. 135 

detonation is communicated with such difficulty that usually only a 
portion of the explosive detonates. 

The effect of penetration of a rifle bullet serves to show a striking 
difference in the sensitiveness of T. N. T. and T. N. A. Bullets fired 
from a service rifle into a box of T. N. T. at a range of about 100 
feet show no effect whatever, while, under similar conditions. T. N. A. 
detonates with great violence. 

T. N. A. is more sensitive to the effect of detonators than is T. N. T. 
Under certain conditions a confined charge of T. N. T. was found to 
require 0.26 gram of mercury fulminate to produce complete detona- 
tion, while a similar charge of T. N. A. required only 0.20 gram of 
fulminate. Under general conditions of use, T. N. A. invariably 
detonates readily and completely with a No. 6 detonator (containing 
1 gram or 15.1 grains of mercury fulminate or its equivalent) . 

Even when moistened with as much as 6 per cent of water, T. N. A. 
detonates completely with a No. 6 detonator, and with 16 per cent 
water detonation was obtained with a No. 6 detonator and a small 
priming charge of dry T. N. A. 

EXPLOSIVE PROPERTIES. 

No data is available at present as to the rate at which T. N. A. 
detonates, but it is undoubtedly very high, probably at least 25,000 
feet per second. The explosive strength is, however, indicated by 
other tests, such as the Trauzl lead block test, which measures the ex- 
pansion produced in a cylindrical hole in a cast lead cylinder about 
8 by 8 inches, by the explosion of 10 grams (about ^ ounce) of the 
explosive. In this test it has been found that T. N. A. gives an ex- 
pansion of about 380 cubic centimeters, as compared with the fol- 
lowing approximate results on other high explosives: Tetryl 320 
c. c, picric acid 300 c. c, T. N. T. 260 c. c. On the basis of this com- 
parison T. N. A. may be regarded as at least 40 per cent stronger 
than T. N. T. 

USE. 

T. N. A. is considerably more expensive to manufacture than T. N. 
T., and for this reason, as well as because of its greater sensitiveness 
to shock, it is not considered suitable for use as a bursting charge for 
high explosive shell, drop bombs, etc. Its sensitiveness is greatly re- 
duced by the addition of as little as 5 per cent of paraffin, or of 25 
per cent of dinitrobenzene, and such mixtures have been loaded in 
shell and fired through armor plate without explosion. Such addi- 
tions to T. N. A. necessarily cause a reduction in explosive strength, 
and these mixtures have therefore not been adopted for use as shell 
explosives. 



136 MILITARY EXPLOSIVES. 

The high cost of T. N. A. constitutes a drawback to the commercial 
as well as the military use of T. N. A. It has, however, been suc- 
cessfully used as an ingredient of cheap, relatively insensitive blast- 
ing explosives, for the purpose of increasing both strength and sensi- 
tiveness to detonation. It has also been used to advantage as a par- 
tial substitute for mercury fulminate in commercial blasting caps or 
electric detonators, where it has the advantage that it can be com- 
pressed to very high densities without losing its sensitiveness to 
detonation under the influence of a small priming charge of ful- 
minate. 

PRECAUTIONS TO BE OBSERVED IN HANDLING AND STORAGE. 

Because of the fact that in the presence of moisture T. N. A. 
undergoes a gradual decomposition even at relatively low tempera- 
tures, it is important that it be kept dry in storage. Efficient ventila- 
tion in the magazine is of great assistance in avoiding dampness. 

The fact that T. N. A. is readily detonated by the effect of rifle 
bullets makes it highly important that it be stored only in bullet- 
proof magazines. Hollow tile construction has been found to be bul- 
let proof. Magazines of lighter type containing T. N. A. should be 
protected by barricades. Exposed doors and window shutters should 
be of heavy iron. 

It must be remembered that T. N. A. can be exploded by friction 
or blows of sufficient force and proper care should be taken to avoid 
unduly rough handling. The wearing of rubber-soled shoes in maga- 
zines is advisable. 

Detonators, blasting caps, dynamite or similar highly sensitive 
explosives, must not be stored in the same magazine with T. N. A. 

INSPECTION. 

The specifications covering the chemical requirements for T. N. 
A., together with the methods for testing, are as follows: 

Nitrogen content: Nitrogen content shall be not less than 25.25 
per cent when tested by the Dumas method. 

Melting point : Melting point shall be not less than 208° C. when 
heated in a capillary tube with a temperature increase of 5° C. per 
minute. 

Insoluble in acetone: The percentage of material in the sample 
which is insoluble in C. P. acetone shall not exceed 0.75 per cent when 
tested as follows: Five grams of the material are thoroughly ex- 
tracted with C. P. acetone in a filtering crucible and the residue dried 
to constant weight at 95° to 100° C. 



MILITAKY EXPLOSIVES. 137 

Moisture : The material shall contain not more than 0.30 per cent 
of moisture when tested as follows: Weigh out 10 grams of the 
sample onto a 3-inch watch glass and dry in an oven at 95° to 100° C. 
for one hour. 

Acidity : The acidity shall not exceed 0.05 per cent when tested as 
follows : Weigh out 10 grams of the sample into a stoppered bottle 
of approximately 250 cubic centimeters capacity, add 150 cubic centi- 
meters of neutral distilled water, and allow to stand at room temper- 
ature with frequent shaking for 30 minutes. Filter off the water 
and wash the residue with two successive 20 cubic centimeter por- 
tions of cool neutral distilled water, adding the washings to preced- 
ing filtrate. Titrate filtrate with N/50 NaOH solution, using 15 
drops of 0.5 per cent phenolphthalein solution as indicator. 



CHAPTER XIII. 

MERCURY FULMINATE. 

Mercury fulminate is the explosive most commonly used for bring- 
ing about the detonation of high explosives. It detonates completely 
and with great violence on mere ignition by means of a flame such 
as the spit from a fuse or by means of an electrically heated wire. 
This fact, together with its property of starting the detonation of 
other explosives, makes it a most suitable detonator material. 

MANUFACTURE. 

It is prepared, generally on a relatively small scale, by the action 
of alcohol on mercury nitrate in nitric acid solution. The raw mate- 
rials required are, therefore, only metallic mercury, nitric acid, and 
ethyl alcohol (common grain alcohol of 95 per cent strength). All 
of these materials must be of high purity, in order to produce a satis- 
factory product. The process of manufacture is quite simple and 
may be carried out as follows: 

About 1 pound of pure mercury is weighed carefully, added to a 
weighed charge of from 8 to 10 pounds of strong nitric acid in a 
suitable bottle or acid pitcher, and allowed to stand until completely 
dissolved, giving a solution of mercury nitrate in the excess of nitric 
acid. A large number of such charges are usually prepared and 
allowed to stand over night until dissolved. 

The acid solution of mercury is then poured into about 8 to 10 
pounds of 95 per cent alcohol which has previously been measured 
into a large thin glass flask or balloon of about 10-gallon capacity 
supported in a suitable rack under an open shed or in the open air. 
A violent reaction results, usually within two or three minutes, the 
mixture in the balloons appearing to be boiling violently as a result 
of the evolution of great quantities of vapors and fumes. These 
vapors, at first white, become brownish red in color toward the 
end of the reaction, as the heat generated drives off nitric acid. At 
this point a small amount of dilute alcohol is usually added to pre- 
vent excessive heating, which would decompose the mercury fulminate 
produced. The reaction usually lasts about one hour, when the fum- 
ing ceases and the liquid remaining in the balloon is found to con- 
tain the crystalline fulminate. 

In some plants the balloons are placed in troughs of water in order 
to control the temperature, and the necks of the balloons are con- 
138 



MILITARY EXPLOSIVES. 139 

nected with a suitable condenser system where the alcohol driven 
off in the fumes is recovered. 

After cooling, the charge in the balloons is dumped onto a cloth 
screen and washed with cold running water until all free acid is 
removed and the fine impurities in the form of " fulminate mud " 
washed away. The washed fulminate is then drained and packed 
in cloth bags, which are usually stored in crocks of water in vaults. 
or in underground concrete tanks of water, until required for use. 
For shipment, the bags are packed in barrels of wet sawdust. 

When required for use, the fulminate is removed from the bags, 
the water drained off, and the wet fulminate spread on cloth to 
dry in dry houses carefully regulated at a temperature of about 
110° F. One pound of mercury produces approximately 1^ pounds 
of dry mercury fulminate. 

CHEMICAL AND PHYSICAL PROPERTIES. 

Mercury fulminate is a heavy, crystalline solid, white when pure, 
but ordinarily of a faint brownish yellow or grayish tint. It has 
practically no tendency to absorb moisture from the atmosphere. 
It is only slightly soluble in water, 100 parts of water at 60° F. dis- 
solving less than 0.01 part of fulminate, and may be kept in contact 
with water for long periods of time without undergoing change. 

The size of the crystals of mercury fulminate is an important fac- 
tor, since it has been determined that very finely divided fulminate, 
consisting mostly of fragments of crystals and usually containing 
an excessive amount of impurities, is less efficient in detonating 
value and strength than larger crystals. In specifying the size of 
crystals desired, however, consideration has been given to the pos- 
sibilities of controlling this feature in manufacture and also to the 
fact that there is some reason to believe that very large crystals of 
fulminate are more sensitive to friction or shock than smaller ones. 
Ordnance Department specifications prescribe that at least TO per 
cent of the crystals shall be within the limits of 0.25 to 0.60 milli- 
meters in length and 0.15 to 0.35 millimeters in diameter. This de- 
termination is readily made under the microscope. 

IMPURITIES. 

Mercury fulminate is required by Ordnance Department specifi- 
cations to be at least 98 per cent pure and the amounts of impurities 
which it may contain are strictly limited. The most objectionable 
impurities are (1) free metallic mercury, for the reason that it 
readily attacks the copper or brass with which it may be in con- 
tact when loaded into fuzes, detonators, or primers, causing the 



140 MILITARY EXPLOSIVES. 

metal to become brittle; (2) acidity, which would cause deteriora- 
tion of the explosive composition and corrosion of metal parts; (3) 
insoluble material, such as sand and grit, which might cause ex- 
plosion of the dry fulminate in the loading operations. If im- 
properly manufactured or incompletely washed, the fulminate may 
also contain various compounds of mercury which might produce 
decomposition and would certainly diminish the explosive efficiency 
of the fulminate. 

ACTION ON METALS. 

Dry mercury fulminate has very little tendency to react with 
metals at ordinary temperature, although to avoid the amalgamat- 
ing effect of any small amounts of free mercury present, the brass 
or copper of the containers is usually varnished or lacquered. Wet 
mercury fulminate, however, reacts with certain metals, especially 
brass, with much greater readiness. 

STABILITY AND SENSITIVENESS. 

Mercury fulminate has been kept for long periods both dry and 
wet, and is believed to undergo practically no change when properly 
manufactured and stored. It is never stored in quantity in the dry 
condition except when loaded into detonators, fuzes, or primers, for 
the reason that when dry, it is readily detonated by friction or 
shock. Whereas, the great majority of high explosives will burn 
without detonating when ignited by a flame, especially if a rela- 
tively small amount of the explosive is ignited, mercury fulminate 
is one .of the so-called " primary " or " initiating " explosives which 
detonate completely on being hea.ted to their ignition point by means 
of a flame or hot wire, thereby becoming suitable for use as detonators 
for other less sensitive explosives. 

The presence of even small amounts of moisture in mercury fulmi- 
nate greatly reduces its efficiency, and as little as 1 per cent is said 
to cause failure to detonate. Fulminate completely saturated with 
water may, however, be detonated by the detonation of dry fulminate 
in contact with it. 

By the usual methods of determining ignition temperature, mer- 
cury fulminate detonates at a temperature of about 100° C. (about 
356° F.), but under varying conditions detonation may result at 
much lower temperatures. The sensitiveness to shock is much greater 
at elevated temperatures than under storage conditions. 

When loaded into commercial detonators, mercury fulminate is 
usually compressed at pressures of about 2,000 or 3,000 pounds per 
square inch. In this condition its explosive properties are not ap- 
preciably different from those of loosely compressed material. At 



MILITARY EXPLOSIVES. 141 

greater densities obtained by higher pressures, there is a gradual re- 
duction in strength, until at such extreme pressures as 75,000 pounds 
per square inch fulminate entirely loses its property of detonating 
and will only burn. In this condition it is referred to as " dead 
pressed." 

Although fulminate can be pressed under very high pressures with- 
out explosion, the presence of any particles of sand or grit is very 
dangerous in any pressing operation. Presses for loading are always 
carefully protected by heavy barricades, and no one is permitted to 
be near the press during operation. 

The readiness with which dry mercury fulminate detonates from 
the effect of blows or friction is the chief reason for the fact that its 
transportation and storage in the dry state is not permitted. Tests 
with a special type of impact machine showed that mercury fulmi- 
nate detonated from the blow of the falling weight dropped from a 
height of only two centimeters (about 0.8 inch), while T. N. T. in the 
same apparatus required a drop oi; about 120 centimeters (48 inches). 

EXPLOSIVE PROPERTIES. 

The efficiency of mercury fulminate as a detonator for other ex- 
plosives can not be judged by its behavior when submitted to the 
usual tests for high explosives. For example, it has been found by 
the usual methods that mercury fulminate has a rate of detonation 
of only about 12,700 feet per second, as compared with the nearly 
double rate for T. N. T. under proper conditions. In the Trauzl lead 
block test, mercury fulminate produces an expansion of only 213 
cubic centimeters, T. N. T. giving about 260 cubic centimeters. 

The results of many investigations have led to numerous theories 
for explaining the unique properties of detonators such as mercury 
fulminate, the general conclusion being that its ability to detonate 
other explosives is due to the rapid development of a very high initial 
rate of detonation which subjects the adjacent mass of explosive to 
a severe shot k or blow, " upsetting " its condition of equilibrium, this 
effect being rapidly transmitted throughout the explosive by a sort of 
wave action which results in complete detonation at a high rate. 

USE. 

Mercury fulminate is used only for the purpose of bringing about 
the detonation of other high explosives or the explosion of propellant 
explosives. In detonators for commercial or military use it may be 
used alone but is generally mixed with from 10 to 20 per cent of 
potassium chlorate, whereby greater efficiency is obtained. Most of 
the commercial detonators or blasting caps and many of those used 



142 MILITARY EXPLOSIVES. 

for military purposes are now composed mainly of tetryl or some 
similar high explosive combined with a smaller priming charge of 
fulminate. The usual grades of detonators contain from 15 to 30 
grains of fulminate or its equivalent. 

The explosion of propellant explosives, as, for example, the smoke- 
less or black powder in small arms cartridges, is effected by the flame 
from a primer or cap, the charge of which is usually a composition 
containing mercury fulminate mixed with other flame-producing 
materials such as potassium chlorate with sulphur or antimony sul- 
phide. The primer is exploded by the impact of the firing pin. 

PRECAUTIONS TO BE OBSERVED IN HANDLING AND STORAGE. 

Mercury fulminate is always stored thoroughly saturated with 
water. It is not advisable to store it for any great length of time in 
the shipping barrels where the bags of wet fulminate are in contact 
with wet sawdust, for the reason that soluble materials extracted 
from the sawdust may cause deterioration of the fulminate. The bags 
should be removed from the barrels and stored in tanks which are 
kept continually full of water and properly protected from sand or 
grit which might penetrate the bags and contaminate the fulminate. 

When left in the barrels during storage, regular inspection must 
be made to insure that the barrels are kept always full of water and 
are not leaking. 

Fulminate must not be stored with any other explosives, for the 
reason that the explosion of even a relatively small amount of dry 
fulminate may cause detonation of the wet materials, the effect of 
which might be to detonate any other high explosives in the vicinity. 

In case of breakage or other cause by which wet fulminate may be 
spilled on the floor, it should not be allowed to dry out before clean- 
ing up. Dry fulminate is very sensitive to friction and must be 
handled with extreme care. 

METHODS OF ANALYSIS. 

The chemical requirements and methods for analysis of mercury 
fulminate as prescribed by the Ordnance Department are as follows : 

It shall (a) be free from acid, (b) contain not more than 2 per cent 
insoluble, (c) contain not more than 1 per cent free mercury, (d) con- 
tain not more than 0.05 per cent chlorine, and (e) be at least 98 per 
cent pure mercury fulminate. 

Acidity: When a 10-gram sample of the thoroughly dried ma- 
terials is placed in a porcelain Gooch crucible having on its bottom 
a filter paper disk, and washed with two successive 25 cubic centimeter 
portions of boiled distilled water, the filtrate so obtained shall show 



MILITARY EXPLOSIVES. 143 

no red tinge upon the addition of 3 drops of methyl orange solution 
made up by dissolving one-tenth gram pure methyl orange in 100 
cubic centimeters of distilled water. 

Insoluble matter: A 2-gram sample of the dry material is dis- 
solved in hot 20 per cent thiosulphate solution, filtered through a 
tared Gooch. The thio solution is washed out with distilled water, 
alcohol, and ether, and the Gooch dried at 60° to 70° C, weighed, 
and insoluble matter calculated. 

Free mercury : The dried fulminate of mercury shall not contain 
over 1 per cent of free mercury when tested as follows: 

Treat the residue in the Gooch crucible used for determining the 
insoluble content of the mercury fulminate with 3 grams of potas- 
sium iodide and grams of sodium thiosulphate dissolved in 50 cubic 
centimeters of distilled water. 

The solution is decanted through the Gooch crucible used in deter- 
mining the insoluble content of the mercury fulminate, and the 
crucible washed thoroughly with distilled water and dried at 80° to 
90° C. for one hour and weighed. The increase in weight of the 
Gooch crucible is taken as the mercury content of the original 
2-gram sample tested and the percentage so determined. 

The potassium iodide converts the organic mercury compounds into 
mercury iodide, which is then soluble in sodium thiosulphate solu- 
tion. The metallic mercury, not being soluble in potassium iodide 
and sodium thiosulphate solution, remains behind as a residue in the 
Gooch crucible, and can therefore be accurately determined. 

Mercury fulminate content: Weigh out exactly three-tenths of a 
gram of the thoroughly dried material that is to be tested and place 
it in a wide-mouthed Erlenmeyer flask containing approximately 250 
•ubic centimeters of distilled water. 

Then add quickly 30 cubic centimeters of a 20 per cent solution 
of sodium thiosulphate that has been freshly filtered to remove any 
precipitated sulphur. The sodium thiosulphate used shall be the 
very best grade obtainable. 

The mixture is shaken for exactly one minute and then at once 
titrated with N/10 hydrochloric acid, using 3 drops of standard 
methyl orange solution as indicator. 

Begin to titrate exactly one minute after the addition of the 
sodium thiosulphate. The bulk of the acid should be added immedi- 
ately and the total time consumed in titration should not exceed one 
minute. 

The per cent of mercury fulminate is calculated from the amount 
of standard acid used after deducting the amount of N/10 hydro- 
chloric acid required to obtain the same end point on a blank deter- 
mination. 



144 MILITARY EXPLOSIVES. 

Four hydrochloric acid molecules are equivalent to one mercury 
fulminate molecule, and therefore 1 cubic centimeter of N/10 
hydrochloric acid is equivalent to 0.00711575 gram of mercury ful- 
minate. 

Chlorides : A 5 -gram sample of the thoroughly dried material is 
placed in a porcelain Gooch crucible having in its bottom a filter 
paper disk and washed with two successive 25 cubic centimeter por- 
tions of distilled water having a temperature between 90° C. and 
100° C. To the filtrate, which is most conveniently caught in a 
test tube, add 3 drops of pure nitric acid having a specific gravity of 
approximately 1.40 and 10 drops of a 10 per cent solution of silver 
nitrate made by dissolving 10 grams pure silver nitrate in 90 cubic 
centimeters of water. If decided turbidity shall appear, rendering 
decision doubtful, make quantitative test; chlorine shall not exceed 
0.05 per cent. 



CHAPTER XIV. 
AMATOL. 

GENERAL. 

Amatol is a mixture of ammonium nitrate and T. N. T. Due to 
the shortage of toluol during the early stages of the war with Ger- 
many, the British Government developed this explosive and adopted 
it after exhaustive tests as a bursting charge for high explosive shells. 
The United States Government shortly after its entrance into the 
war and for similar reasons authorized its use as follows : 50/50 for 
shells for 75 mm. up to and including 4.7 inches; 80/20 for shells 
from 4.7 inches up to and including 9.2 inches. The ingredients are 
mixed by weight. The first figure refers to ammonium nitrate, the 
second to T. N. T. 

PROPERTIES. 

Amatol is hygroscopic, insensitive to blows or friction, yet can be 
detonated by severe impact, has no tendency to form dangerous com- 
pounds with metal other than copper or tin, is more insensitive to 
explosion by influence than T. N. T., and has approximately the 
same rate of detonation and strength as T. N. T. 

MANUFACTURE OR METHOD OF MIXING. 

The T. N. T. is melted and incorporated with the ammonium 
nitrate in a jacketed mixer for a length of time sufficient to insure 
each grain of the ammonium nitrate being thoroughly coated with 
the T. N. T. The 50/50 mixture is sufficiently fluid to admit of its 
being poured or cast. The 80/20 mixture is plastic, resembling 
moist brown sugar, and must be loaded into the shell by tamping 
or screw filling. 

ANALYSIS. 

Raw materials. — The ammonium nitrate and T. N. T. used in the 
preparation of amatol must conform to Ordnance Department 
specifications governing these materials, as impurities in both have 
harmful effects on the resulting product. Oily impurities in the T. 
N. T. will cause exudation or leakage, while impurities in ammonium 
nitrate, such as pyridine, cyanide, etc., will cause formation of gas 
or frothing, resulting in probable cavitation in the shell. Methods 
132569—19 12 145 



146 MILITARY EXPLOSIVES. 

of analysis for governing the inspection of these materials are given 
elsewhere in this book. 

Sampling. — Samples should be taken from the mixer while the 
stirrers are rotated, as the T. N. T. and ammonium nitrate have a 
tendency to segregate. It is desirable to take the sample in an alumi- 
num or thin sheet-iron vessel, a circular piece of stout cardboard be- 
ing placed in the bottom. To obtain concordant results with dupli- 
cate analyses, experience will show that extreme care must be taken 
with the samples. 

Moisture. — Dish and dome method: Heat an aluminum dish and 
dome (cover) for 15 minutes, cool in the desiccator and weigh. Add 
approximately 5 grams of the sample and place on the top of a water 
oven for 3 hours. Cool in a desiccator for 20 minutes and weigh. 
Loss in weight equals moisture present in the original sample. A 
small quantity of T. N. T. sublimes but condenses on the inside of 
the cover, which should be cleaned thoroughly before using in an- 
other test. 

T. N. T. — Extraction with benzene: Fold a dry filter paper so 
as to leave a small cavity in the center and weigh in a tared weigh- 
ing bottle. Place about 2 grams of powdered amatol in the filter 
paper without removing it from the bottle and reweigh. Transfer 
the paper and amatol to a small funnel and wash with approxi- 
mately 75 c. c. hot benzene, adding enough at a time to cover the 
powder. After about one-half of the benzene has been added the 
remainder can be poured in rapidly, taking care to wash the sides 
of the filter paper thoroughly. Transfer the filter paper and resi- 
due from the funnel to the top of a steam oven in order to remove 
the greater portion of the benzene and dry in a tared weighing bot- 
tle for one hour. Loss in weight equals T. N. T. plus moisture. 

Ammonium nitrate. — Extraction with water: A known weight, 
approximately 2 grams, is extracted with 50 c. c. warm water, 
temperature not less than 85° C. After cooling, the solution is fil- 
tered and the process repeated three times with 50 c. c, 30 c. c.,.and 
20 c. c. successive quantities of hot water. The combined filtrations 
are evaporated just to dryness in a tared dish and left in a vacuum 
desiccator overnight. Rinse the residue two or three times with 
CP ether. Dry on top of the oven to remove ether vapors, cool and 
weigh, residue equaling ammonium nitrate present in the sample. 



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Copisarow, M. T. N. T. 1915. Chem. News, v. 112, pp. 147-8. Purification of 

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Corbin. Coating difficulty inflammable explosives with a thin layer of black 

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Cronquist, A. W. Powders and explosives ; old and new studies. 1908. Chem. 

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Curphey, W. S. Alkali inspector's report for 1917. 1918. Chem. Absts., v. 12, 

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Dautriche, M. H. Some properties of picric acid, T. N. T., and trinitrobenzene. 

1912. Chem. Absts., v. 6, p. 1226. T. N. T. 
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1912. Chem. Absts.. v. 6, p. 1226. Picric acid. 

Delvigne, M. Explosive. (Pat.) 1911. Chem. Absts., v. 5, p. 786. Ammonium 
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Dow, H. H. Phenol synthetically. (Pat.) V. 12, p. 1969. Phenol. 

Du Pont, Francis. Apparatus for forming black gunpowder. 1910. Chem. 
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Du Pont. Apparatus for solidifying crystallizable mixtures (e. g., black gun- 
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1913. Official Gaz.. v. 205, p. 175. Black powder. 



150 MILITARY EXPLOSIVES. 

Du Pont. Making black gunpowder having approximately spherical grains. 

1914. Chem. Absts., v. 8, p. 3228. Black powder. 
Du Pont. Apparatus for shaping gunpowder into approximately spheri- 
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Du Pont. Gunpowder corning mill. 1915. Chem. Absts., v. 9, p. 153. (Pat.) 

Black powder. 
Du Pont de Nemours & Co. High explosives. Catalogue. Section I. 1915. 

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Du Pont de Nemours & Co. High explosives. (Catalogue.) Section II. 1915. 

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Dynamite Act Ges. V. A. Nobel. Process of obtaining a liquid mixture of 

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Soc. Chem. Ind., v. 9, p. 385. Picric acid. 
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Picric acid. 
Escales, R. Improvements in T. N. T. explosives. 1908. Chem. Absts., v. 2, 

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Escales, R. Schwarzpulver und Sprengsalpeter. 1914. Pp. 376-80, 381-403, 

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Escales, R. Nitrosprengstoffe. 1915. Pp. 180, 360. Ammonium picrate. 
Escales, R. Nitrosprengstoffe. 1915. Pp. 177-9, 336-8, 347-52. Picric acid. 
Escales, R. Nitrosprengstoffe. 1915. Pp. 145-61. T. N. T. 
Farmer, R. C. (See under Craig, R., Robertson, R., Farmer, R. C, Rotter, G. ) 

T. N. T. 
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1913.. 1914. U. S. Bur. of Mines, Technical Paper 85, pp. 5-, 6-13. Black 

powder. 
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U. S. Bur. of Mines, Technical Paper 107. Pp. 5, 6-14. Black powder. 
Fay, A. H. Production of explosives in the United States during 1915. 1916. 

Bur. of Mines, Technical Paper 159, p. 5. Black powder. 
Fay, A. H. Production of explosives in the United States during 1916. 1917. 

U. S. Bur. of Mines, Technical Paper 175, pp. 5, 6-22. Black powder. 
Fay, A. H. Production of explosives in the United States during 1917. 1918. 

U. S. Bur. of Mines, Technical Paper 192, pp. 8, 6-14. Black powder. 
Fletcher, B. H. (See under Arthur and Fletcher, B. H.) T. N. T. 
Flurschlim, B. J. Nitrating toluene containing paraffin hydrocarbons. (Pat. i 

1917. Chem. Absts., v. 11, p. 2045. T. N. T. 
Gardner, H. A. Picric acid. (Pat.) 1917. Chem. Absts., v. 11. p. 2407. Pic- 
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Gaudechon, H. (See under Berthelot, D., and Gaudechon, H.) Ammonium 

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Gewerkschaft des Steinkohlenbergwerks Lothringen und Uhde. Pure am- 
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p. 1141. Picric acid. 



MILITARY EXPLOSIVES. 151 

Girard, C. Explosive. (Pat.) 1908. Chera. Absts., v. 2, p. 3283. Picric acid. 
Giua, M. The T. N. T. industry in Italy and its conditions of development. 

1915. Chem. Absts., v. 9, p. 3361. Preparation of T. N. T. 1916. Chem. 

Absts., v. 10, p. 969. T. N. T. 
Gutensohn, A. Producing picric. (Pat.) 1901. Jnl. Soc. Chem. Ind., v. 20, 

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Guttmann, O. The dangers in the manufacture of explosives. 1892. Jnl. Soc. 

Chem. Ind., v. 11, p. 210. Picric acid. 
Guttmann, Oscar. The manufacture of explosives. V. II. 1895. P. 236. 

E. C. blank fire. 
Hall, C. Apparatus and methods for physical testing of explosives. 1911. 

Bur. Mines, Bui. v. 15, pp. 79-82, 88-117. Picric acid. 
Hall, C. Apparatus and methods for physical tests of explosives. 1911. 

U. S. Bur. Mines, Bui. 15, pp. 79-82, 88-117. Permissible explosives. 1912. 

U. S. Bur. Mines, Cir. 6, pp. 9-10. T. N. T. 
Hall, Clarence. Apparatus and methods for physical tests of explosives. 

1911. U. S. Bur. of Mines, Bui. 15, pp. 79-82, 88-117. Black powder. 
Hall, C. (See under Munroe, C. E., and Hall, C.) Phenol. 
Hall, C. .(See under Munroe and Hall.) Picric acid. 
Hall, C, and Howell, S. P. Tests of permissible explosives. 1913. Bur. of 

Mines, Bui. 66, pp. 4-12, 15-22. Ammonium picrate. 
Hall, C, and Howell, S. P. Tests of permissible explosives. 1913. Bur. of 

Mines, Bui. 66, pp. 4-12, 15-22. Black powder. 
Hall, C, and Howell, S. P. Tests of permissib'.e explosives. 1913. Bur. of 

Mines, Bui. 66, pp. 4-12, 15-22. Picric acid. 
Hamilton, Alice. Industrial poisons encountered in the manufacture of ex- 
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Hamilton, Alice. Industrial poisons encountered in the manufacture of ex- 
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Haussermann, C. Explosive properties of T. N. T. 1914. Chem. Absts., v. 8, 

p. 249. T. N. T. 
Heden, J. Wood pulp, oxalic acid, and picric acid. (Pat.) 1909. Chem. Absts.. 

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Hesse, Bern hard. T. N. T. 1917. Oil, Paint and Drug Reporter, v. 92, p. 87, 

No. 7. T. N. T. 
Hibbard. Black powder. (Pat.) 1914. Chem. Absts., v. 8, p. 3629. Black 

powder. 
Higgins. Prevention of accidents from explosives in metal mining. 1914. Bur. 
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Hoefman, E. J. Nitration of toluene. 1916. U. S. Bur. of Mines, Technical 

Paper 146, pp. 5, 8-12. T. N. T. 
Howell, S. P. (See under Hall, C, and Howell, S. P.) Ammonium picrate. 
Howell, S. P. (See under Hall, C, and Howell, S. P.) Black powder. 
Howell, S. P. (See under Hall, C, and Howell, S. P.) Picric acid. 
Howell, S. P., and Tiffany, J. E. vMethods for routine work in the explosives 

physical laboratory of the Bureau of Mines. 1918. Bur. of Mines, Technical 

Paper 186. 63 pp. Ammonium picrate. 
Howell, S. P., and Tiffany, J. E. Methods for routine work in the explosives 

physical laboratory of the Bureau of Mines. 1918. Bur. of Mines, Technical 

Paper 186, pp. 1, 3-7, 11-21, 25-43. Black powder. 
Howell, S. P., and Tiffany, J. E. Methods for routine work in the explosives 

physical Moratory of the Bureau of Mines. 1918. Bur. of Mines, Technical 

Paper 186. 63 pp. Picric acid. 



152 MILITAKY EXPLOSIVES. 

Howell, S. P., and Tiffany, J. E. Methods for routine work in the explosives 

physical laboratory of Bureau of Mines. 1918. Bur. of Mines, Technical 

Paper 186: 63 pp. T. N. T. 
Humphrey, Irwin. Nitration of toluene to T. N. T. 1916. Jnl. Ind. & Engng. 

Chem., v. 8, pp. 998-9. T. N. T. 
Imray, O. Manufacture of explosives. (Pat.) 1892. Jnl. Soc. Chem. Ind., 

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Johnson, F. M. G. Separating T. N. T. from spent acid. (Pat.) 1918. Chem. 

Absts., v. 12, p. 2055. T. N. T. 
Kohleb, H. Herstellung von Pikrinsaure. (Pat.) 1893. Jahresber. d. Leist. 

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Kolowratnik, R. Picric acid explosive. (Pat.) 1913. Chem. Absts., v. 7, 

p. 3665. Picric acid. 
Kullgren, Carl. Action of atmosphere, moisture on moisture content and rate 

of combustion of black powder. 1912. Chem. Absts., v. 6, p. 425. Black 

powder. 
Lanfrey, A. C. Preventing the reactivity of moist picric acid. 1912. Chem. 

Absts., v. 6, p. 2533. Picric acid. 
Langenscheidt, F. Preparation of T. N. T. 1913. Chem. Absts., v. 7, p. 1416. 

T. N. T. 
La Sueur, E. A. N. Y. meeting of American Inst, of Chem. Engrs. 1914. Chem. 

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Legge, T. M. T. N. T. poisoning. 1917. Jnl. Soc. Chem. Ind., v. 37, pp. 326-7. 

T. N. T. 
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T. N. T. 
McHutchinson and Wright, R. The precipitation of T. N. T. from concen- 
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MacDonald, G. W. Nobel's patents. 1911. Chem. Absts., v. 5, p. 2331. Sport- 
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Magnin. Action of Roentgen rays on various kinds of powders. 1914. Chem. 

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Marckwald, W. Color of picric acid and its solutions. 1900. Jnl. Soc. Chem. 

Ind., v. 19, p. 433. Picric acid. 
Mardick, J. R. Nitro-compounds from tar. (Pat.) 1917. Chem. Absts., v. 

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Mardick. Nitro-compounds from tar. 1917. Chem. Absts., v. 11. p. 2154. 

Black powder. 
Marshall, A. Explosives. 1917. 2d ed. Ammonium picrate, v. 1, pp. 746-7. 

Black powder, v. 1, pp. 8-9. E. C. blank fire powder, v. 1, p. 48. Picric acid, 

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Martin, G. Industrial nitrogen compounds. 1915. P. 114. E. C. powder. 
Matter, O. Detonating caps for explosives. (Pat.) 1917. Chem. Absts., v. 

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Meyer and Berguis. Preparation of phenol from chlorobenzene. 1915. Chem. 

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Molinari, E., and Quartieri, F. T. N. T. 1914. Chem. Absts., v. 8, p. 422. 

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18, p. 447. Ammonium picrate. 



MILITARY EXPLOSIVES. 153 

Mosenthal, H. Life work of A. Nobel. 1899. Jnl. Soc. Chem. Ind., v. 18, p. 

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Munroe, Charles. Chemicals and allied products produced in the United 

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Munroe, C. E., and Hall, C. A primer on explosives for coal miners. 1911. 

Bur. Mines, Bui. 17, p. 22. Picric acid. 
Munroe, C. E., and Hall, C. A primer on explosives for coal miners. 1911. 

Bur. of Mines, Bui. 17, p. 22. Phenol. 
Murray, Alexander. Manufacture of picric acid. 1919. Chem. Absts., v. 13, 

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Myrin, O. Several modern military explosives. 1916. Intern. Mil. Digest, 

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Nathan, F. L., Rintoul, W., and Baker, F. Explosives. 1913. Chem. Absts., 

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Nathhurst, Jalmar. T. N. T. mixture for use in explosives. (Pat.) 1910. 

Chem. Absts., v. 4, p. 3300. T. N. T. 
Ney, A. H. Synthetic phenol and picric acid. 1915. Met. and Chem. Engng., 

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Ney, A. H. Synthetic phenol and picric acid. 1915. Met. and Chem. Engng., 

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Nitroglycerine Aktins. (Nauckhoff.) Ammonium nitrate. (Pat.) Chem. 

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Nobel's Researches. 1910. Chem. Absts., v. 4, p. 1544. Sporting ballistite. 
Oberschlesische Akt. Ges. f. Fabrikation von Lignose Schiesswollfabrik 

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Oddo, B. Determination of nitrogen in nitric ester explosives. 1918. Chem. 

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Osborne, Thos. Picric acid ; its manufacture and liability to explode. 1915. 

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Ost, H. Lehrbuch der Chemischen Technologic 1911. Pp. 201-3. Black 

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Penna. Dept. of Labor and Industry. Safety standards of the Industrial 

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Pope, Frederick. Mechanical engineering of a synthetic phenol plant. 1916. 

Chem. and Met. Engng., v. 15, pp. 185-92. Phenol. 
Porter, H. C, and Storm, C. J. Coal tar products. 1915. Bur. of Mines, 

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Porter, H. C, and Storm, C. G. Coal-tar products. 1915. Bur. of Mines, 

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Porter, H. C, and Storm, C. G. Coal-tar products. 1915. Bur. of Mines, Tech- 
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Porter, H. C, and Storm, C. G. Coal-tar products. 1915. Bur. of Mines, 

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Quartieri, F. (See under Molinari, E., and Quartieri, F.) T. N. T. 
Quartieri, F.. and Soc. Italiana Prodetti Explodenti. Explosives. (Pat.) 

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154 MILITARY EXPLOSIVES. 

Reuter, O. Liquid explosive. (Pat.) 1916. Chem. Absts., v. 10. p. 694. 

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Rice, Archie. Risk and avoidance of T. N. T. poisoning. 1918. Chem. Absts., 

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Rintoul, W. Melting point of 1, 2, 4, 6, trinitrotoluene. 1915. .Tnl. Soc. 

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Rittman, W. The utilization of aromatic compounds derived from cracked 

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Robertson, R. (See under Craig, R., Robertson, R., Farmer, R. C, Rotter. G. ) 

T. N. T. 
Rogers, Allan. Industrial chemistry. 1915. P. 399, 477. Phenol. 
Rotter, G. (See under Craig, R., Robertson, R., Farmer, R. C, Rotter. <;.i 

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Runge, W. Primer for explosives. (Pat.) 1916. Chem. Absts., v. 10, p. 822. 

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Rutledge, J. J. The use and misuse of explosives in coal mining. 1913. U. S. 

Bur. of Mines, Cir. 7, pp. 7-9, 11. Black powder. 
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Sanford, P. G. Nitroexplosives. 1906. Pp. 186-187. E. C. blank fire powder. 
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Schuppert. Fires in gunpowder (black powder) factories. 1910. Chem. Absts., 

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Shrotter, F. T. N. T. 1913. Chem. Absts., v. 7, p. 3663. T. N. T. 
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Snelling, W. O., and Cope, W. C. The rate of burning of fuse. 1912. Bureau 

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Snelling, W. O., and Storm, C. G. The analysis of black powder and dyna- 
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MILITAKY EXPLOSIVES. 155 

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Thompson, W. P. Process for manufacture of pictric acid from crude phenols. 

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Thorpe, Edw. Dictionary of applied chemistry. 1912. P. 6569. Vol. 1. 

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Tyrer, D. Phenol. (Pat.) 1917. Chem. Absts., v. 11, p. 277. Phenol. 
U. S. Navy Department Specifications for T. N. T. 1917. Jul. Soc. Chem. Ind.. 

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Phenol. 
Vennin, L., et Chesneau, G. Les poudres et explosifs. 1914. P. 271. Picric 

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Voigt, A. Grounding of machinery for powder manufacture. 1911. Chem. 

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Wallace, R. N. Phenol. (Pat.) 1918. Chem. Absts., v. 12, p. 1969. Phenol. 
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Waller, C. E. Method of calculating comparative strength and efficiency of 

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156 MILITARY EXPLOSIVES. 

Wilkinson, T. S. Military explosives. 1916. Chem. Absts., v. 12, p. 68. Picric 

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Wolffenstein, R. (See under Boeters and Wolffenstein, R.) Picric acid. 
Woodbury. Varying the velocity of detonation of explosives containing am- 
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38-9. Picric acid. 

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